Regulatory b cells and their uses

ABSTRACT

The present invention relates to a phenotypically distinct CD1d high  CD5 +  B cell subset that regulates T cell mediated inflammatory responses through the secretion of interleukin-10 (IL-IO). The invention also relates to the use of these IL-IO producing regulatory B cells in the manipulation of immune and inflammatory responses, and in the treatment of disease. Therapeutic approaches involving adoptive transfer of these regulatory B cells, or expansion of their endogenous levels for controlling autoimmune or inflammatory diseases and conditions are described. Ablation of this subset of regulatory B cells, or inhibition of their IL-IO production can be used to upregulate immunodeficient conditions, and/or to treat tumors/cancer. Diagnostic applications also are encompassed.

This application claims and is entitled to priority of U.S. ProvisionalPatent Application No. 61/125,680, the content of which is incorporatedby reference herein in its entirety.

1. INTRODUCTION

The present invention relates to a phenotypically distinctCD1d^(high)CD5⁺ B cell subset that regulates T cell mediatedinflammatory responses through the secretion of interleukin-10 (IL-10).The invention also relates to the use of these IL-10 producingregulatory B cells in the manipulation of immune and inflammatoryresponses, and in the treatment of disease. Therapeutic approachesinvolving adoptive transfer of these regulatory B cells, or expansion oftheir endogenous levels for controlling autoimmune or inflammatorydiseases and conditions are described. Ablation of this subset ofregulatory B cells, or inhibition of their IL-10 production can be usedto upregulate immunodeficient conditions, and/or to treat tumors/cancer.Diagnostic applications are also encompassed.

2. BACKGROUND

The immune response can loosely be divided into two components: thehumoral immune response which involves antibody formation, and thecell-mediated immune response which involves the activation ofmacrophages, natural killer (NK) cells, antigen-specific cytotoxicT-lymphocytes, and the release of various cytokines in response toantigen. Typically, B lymphocytes (B cells) are characterized by theirrole in antibody production; whereas T lymphocytes (T cells) arecharacterized by their role in cell-mediated immunity. However, B cellspossess additional immune functions, including the production ofcytokines, and the ability to function as antigen presenting cells(APCs).

Once generated, immune responses need to be regulated to prevent theresponding effector cells from causing harmful effects. Immunoregulationhas traditionally been thought of as a function of T cells. Functionallydistinct regulatory T cell subsets have been identified and clearlydefined. For example, helper T cells that up-regulate the immuneresponse include T helper type 1 (Th1) cells that regulate cell-mediatedimmune responses, and T helper type 2 (Th2) cells that regulate thehumoral immune response. Suppressor T cells crucial for the maintenanceof immunological tolerance, currently referred to as T regulatory cells,include IL-10-producing T regulatory 1 (Tr1) cells, and TGF-β1-producingT helper type 3 (Th3) cells. Recent studies of autoimmune conditionsgave rise to the notion that B cells may also participate inimmunoregulation. However, regulatory B cell subsets have not beenclearly defined.

Multiple roles for B cells have been implicated in autoimmune diseases.B cells, a major immune cell population, can play a pathogenic role inacquired immune responses by producing autoantibodies that drive thedevelopment of autoimmune diseases. Certain therapies developed fortreating autoimmunity are aimed at depleting pathogenic B cells.However, the tools currently available are not specific for thepathogenic B cells and deplete most B cells. For example, B celldepletion in humans using CD20 monoclonal antibody (mAb) can beeffective in treating patients with various autoimmune disorders, suchas rheumatoid arthritis and lupuS (Edwards et al., 2001, Rheumatol.40:205-11; Edwards et al., 2005, Rheumatol. 44:151-56; El Tal et al.,2006, J. Am. Acad. Dermatol. 55:449-59; Anolik et al., 2004, Arth.Rheum. 50:3580-90; Stasi et al., 2007, Blood 110:2924-30). CD20 is a Bcell-specific marker that is first expressed on the cell surface duringthe pre-B to immature B cell transition, but is lost upon plasma celldifferentiation (Tedder & Engel, 1994, Immunol. Today 15:450-54; Uchidaet al., 2004, Int. Immunol. 16:119-29). A recent phase II trial usinganti-CD20 antibodies indicates clinical efficacy in multiple sclerosis(MS) patients (Hauser et al., 2008; N. Engl. J. Med. 358:676-88).However, the mechanisms underlying the effect of B cell depletion ondisease activity remains unknown. On the flip side, B cell depletion mayexacerbate disease. Indeed, B cell depletion was recently found toexacerbate ulcerative colitis in human clinical trials (Goetz et al.,2007, Inflamm Bowel Dis. 13:1365-8) and may contribute to thedevelopment of psoriasis (Dass et al., 2007, Arthritis Rheum.56:2715-8).

Over a decade ago, Janeway and colleagues (Wolf et al., 1996, J. Exp.Med. 184: 2271-2278) described studies designed to assess the role of Bcells in the course of autoimmune disease by inducing acute experimentalautoimmune encephalomyelitis (EAE) in B cell-deficient mice. EAE is anautoimmune disease of the central nervous system (CNS) that models humanmultiple sclerosis. Results showed that elimination of B cells did notprevent induction of autoimmunity. Instead, the lack of B cells seemedto exacerbate disease outcome, in that the B cell deficient mice did notfully recover as compared to wild-type mice. Thus, while B cells supplythe autoantibodies thought to be responsible for disease, theseinvestigators concluded that B cells are not required for activation ofdisease, and instead, that their presence is required to enhancerecovery. More recently, it was reported that B cell IL-10 productioncorrelated with recovery from EAE, a Th1-mediated autoimmune disease(Fillatreau et al., 2002, Nature Immunol. 3: 944-950). IL-10 is animmunoregulatory cytokine produced by many cell populations. IL-10 hasbeen shown to suppress cell-mediated immune and inflammatory responses.

Other recent studies in mouse models indicate that B cells and IL-10play a protective role in T cell-mediated inflammation, e.g., inTh2-mediated inflammatory bowel disease (Mizoguchi et al., 2002,Immunity 16:216-219), and in contact hypersensitivity (CHS) responses—acutaneous inflammatory immune reaction that is mediated by T cells insensitized individuals following subsequent contact with the sensitizingantigen (Enk, 1997, Mol. Med. Today 3:423-8). In particular, mice with Bcells deficient for CD19 expression (CD19^(−/−)) have augmented CHSresponses (Watanabe et al., 2007, Am. J. Pathol. 171:560-70). IL-10 mustbe involved in protection since neutralizing IL-10 through mAb treatmentenhances CHS responses, while systemic IL-10 administration reduces CHSresponses (Ferguson et al., 1994, J. Exp. Med. 179:1597-1604; Schwarz etal., 1994, J. Invest. Dermatol. 103:211-16).

On the basis of these and othei studies, it has been proposed that, liketheir T cell counterparts, B cells can be divided into functionallydistinct regulatory subsets capable of inhibiting inflammatory responsesand inducing immune tolerance by mechanisms that include IL-10 and TGF-βproduction, secondary antigen presentation, and interactions with otherimmune cells either directly or through secreted antibodies. (Forreviews on the subject, see Mauri & Ehrenstein, 2007, TRENDS in Immunol.29: 34-40; and Mizoguchi & Bhan, 2006, J. Immunol. 176:705-710).

However, it remains unclear whether regulatory B cells represent aunique regulatory lineage tasked with maintaining self-tolerance the waythat naturally occurring regulatory T cells are. The generation ofregulatory B cells has been reported in multiple mouse models of chronicinflammation, although their existence in normal mice remains unknown(Mizoguchi & Bhan, 2006, J. Immunol. 176:705-10). Despite theidentification of a regulatory B cell subset generated in these mousemodels, no definitive murine phenotype has been established and, infact, only a general list of cell-surface markers envisioned topotentially associate with regulatory B cells exists (Mauri &Ehrenstein, 2007, Trends Immun. 29:34-40). Furthermore, the existence ofregulatory B cells in humans remains a matter of speculation, and thepotential phenotypic markers for human regulatory B cells are unknown(Mauri & Ehrenstein, 2007, Trends Immun. 29:34-40). A role for CD40 inthe generation of regulatory B cells and the induction of IL-10production by these cells has been postulated (Inoue et al., 2006 CancerRes. 66:7741-7747). Nonetheless, it has yet to be proven whether CD40can be directly targeted, i.e., with anti-CD40 antibodies, as a means togenerate regulatory B cells in vivo (Mauri & Ehrenstein, 2007, TrendsImmun. 29:34-40).

Further complicating these issues, during immune responses, IL-10 isalso secreted by multiple cell types, including T cells, monocytes,macrophages, mast cells, eosinophils, and keratinocytes, and cansuppress both Th1 and Th2 polarization and inhibit antigen presentationand proinflammatory cytokine production by monocytes and macrophages(Asadullah et al., 2003, Pharmacol. Rev. 55:241-69). Clearly, it isunknown whether multiple B cell populations or a novel B cell subsetregulates inflammatory responses, whether regulatory B cells produceIL-10 or other cytokines directly, whether regulatory B cells havepotent activities in vivo, whether humans possess regulatory B cells,how regulatory B cells can be activated and/or expanded, and the role ofregulatory B cells in disease. To advance therapeutic application,subsets of immunoregulatory B cells need to be better defined and theirphenotype will need to be more closely correlated with their function invivo.

3. SUMMARY

The present invention relates to a phenotypically distinctCD1d^(high)CD5⁺ B cell subset that regulates T cell mediatedinflammatory and immune responses through secretion of IL-10. Theinvention also relates to harnessing this regulatory B cell subset forthe manipulation of immune and inflammatory responses in humans andother mammals. Treatments for diseases associated with diminished IL-10levels, such as inflammatory and autoimmune diseases are described, aswell as treatments for diseases associated with elevated IL-10 levels,such as immunosuppression and cancer.

Cellular compositions enriched for the CD1d^(high)CD5⁺ B cell subset,and methods for their preparation are described. The invention relates,in part, to the discovery that a cellular composition that has beenenriched by selection using both CD1d^(high) and CD5 as cellular markerswill contain a higher percentage of IL-10 producing B cells than apopulation enriched using only one of these markers. These cellularcompositions can be expanded and used to treat inflammatory and/orautoimmune conditions or diseases by adoptive transfer. In analternative approach, therapeutic regimens designed to expand theendogenous population of the CD1d^(high)CD5⁺ B cell subset in subjectsin need of such treatment can be used to treat inflammatory and/orautoimmune conditions or diseases. In this approach, antibodies thatactivate and/or stimulate expansion of the regulatory B cell subset, orincrease their production of IL-10 can be used.

In an alternative embodiment, methods are described for treatingdiseases and/or conditions involving immunosuppression or cancer bydepleting or ablating the CD1d^(high)CD5⁺ regulatory B cell subset insubjects in need thereof. In this approach, antibodies that kill theregulatory B cell subset, or inhibit their proliferation or theirproduction of IL-10 can be used.

In yet another embodiment, methods for identifying the regulatory B cellsubset in patients and/or patient samples are described for diagnosingthe immune status of affected individuals.

The invention is based, in part, on the identification of a rareregulatory B cell subset that controls T cell-mediated immune andinflammatory responses in vivo. The principles of the invention areillustrated in animal models in the studies described in the examples,infra, and resolve previously unexplained contradictions reported in theliterature for the role of B cells in disease models such as EAE,arthritis, and inflammatory bowel disease. The examples described infrademonstrate:

-   -   a phenotypically unique B cell subset with potent regulatory        activities in vivo;    -   a reliable method of intracellular cytokine staining that        clearly identifies CD1d^(high)CD5⁺ regulatory B cells as the        IL-10-producing B cell subset;    -   adoptive transfer of this CD1d^(high)CD5⁺ cell subset has potent        IL-10-dependent regulatory functions during inflammation in        vivo, which can apply to other T cell-mediated inflammatory or        autoimmune diseases;    -   expansion of the unique regulatory B cell subset in human CD19        transgenic mice results in a decreased inflammatory response;    -   the absence of this unique B cell subset in CD19-deficient mice        results in augmented T cell-mediated inflammation; and    -   the presence of this unique IL-10-producing B cell subset in        healthy wild type mice (1-2% of spleen B cells) and expansion of        the population during contact hypersensitivity responses.

The phenotypic markers described herein were identified in murinemodels; a cognate human regulatory B cell subset that produces IL-10 isencompassed by the invention. This regulatory B cell subset will bephenotypically distinct from other B cell populations, and may beidentified by transcription factors responsible for displaying the samecell surface markers; i.e., CD1d^(high)CD5⁺.

4. DESCRIPTION OF THE FIGURES

FIG. 1: B cell regulation of T cell-mediated inflammatory responses. CHSresponses in (A) wild type, hCD19Tg, and CD19^(−/−) mice, (B) hCD19Tgmice treated with hCD19 or isotype control mAb 7 days before or 2 daysafter initial oxazolone sensitization, and (C) wild type or (D)CD19^(−/−) mice treated with CD20 or isotype control mAb 7 days beforeor 2 days after first sensitization with oxazolone. The increase in earthickness was measured at various time points after oxazolone challenge.Values represent means (±SEM) from ≧4 mice of each group. Horizontaldashed lines representing the average increase in ear thickness at 48hours after oxazolone challenge in wild type mice is shown forcomparison. Significant differences between sample means are indicated;*p<0.05; **p<0.01, NS, differences between means were not significant.Similar results were obtained in at least two independent experiments.

FIG. 2: IL-10 production by spleen B cells from wild type, hCD19Tg, andCD19^(−/−) mice. (A) Representative flow cytometry histograms showing Bcell purities after B220-mAb coated microbead isolation. (B) Luminex and(C) ELISA determinations of secreted IL-10 protein levels by purifiedB220⁺ cells cultured in media alone or containing LPS, or anti-CD40 mAbplus anti-IgM antibody. Values are means (±SEM) from ≧3 mice of eachgroup. (D) Frequency of IL-10-secreting B cells determined by ELISPOTassay. Purified B220⁺ cells were incubated in the absence or presence ofLPS for 24 h. Values represent mean numbers (±SEM) of spot-formingcolonies per 10⁵ B220⁺ cells from ≧3 mice of each group. B-D).Significant differences between sample means are indicated; *p<0.05,**p<0.01. Results represent one of two independent experiments producingsimilar results.

FIG. 3: Cytokine production by B cells from wild type, hCD19Tg, andCD19^(−/−) mice. (A) Splenocytes without stimulation, or (B) spleen, (C)peritoneal cavity, (D) blood, (E) peripheral lymph node, and (F)mesenteric lymph node lymphocytes after culture with LPS, PMA,ionomycin, and monensin for 5 h. The cells were stained with B220 mAb(except peritoneal cavity) and/or CD19 or CD20 mAbs to identify B cells.After permeabilization, the cells were stained with anti-IL-10 mAb.During flow cytometry analysis, B220 staining was used as the initialgate for identifying B cells (except peritoneal cavity). All data arerepresentative of 3 independent experiments with 3 mice in each group.Representative results for one mouse are shown demonstrating thefrequency of IL-10-producing cells among total B cells within theindicated gates. Bar graphs indicate mean (±SEM) percentages and numbersof B cells that produced IL-10 in the one representative experiment.Significant differences between sample means are indicated: **, p<0.01.(G) Representative isolation of IL-10 secreting B cells. Purifiedsplenic B220⁺ cells from three hCD19Tg mice were pooled and stimulatedwith LPS, PMA, and ionomycin for 5 hours before staining for IL-10secretion and CD19 expression (left panel). IL-10⁺ and IL-10⁻ B cellswere isolated by cell sorting using the indicated gates and subsequentlyreassessed for IL-10 secretion and CD19 expression (right panels). (H)Microarray analysis of cytokine gene expression by IL-10-secreting Bcells versus B cells not secreting IL-10 after purification as in (G).Mean fold-differences (±SEM) in cytokine transcript expression levelsfrom three independent experiments are shown. Values of 1 indicate nodifference. Significant differences between IL-10⁺ and IL-10⁻ cellssample means are indicated: **, p<0.005.

FIG. 4: IL-10 production by non-B cells from wild type, hCD19Tg, andCD19^(−/−) mice. Splenocytes were cultured with LPS, PMA, ionomycin, andmonensin for 5 hours before staining with CD 19 or CD20 mAbs to identifyB cells. After permeabilization, the cells were stained with anti-IL10mAb and assessed by flow cytometry. Representative histograms showresults with single mice while the bar graph indicates results for allsamples. Values represent the percentage of IL-10-producing cells amongtotal non-B cells. All data are representative of 3 independentexperiments with 3 mice in each group.

FIG. 5: Phenotype of IL-10-producing B cells. (A) CD1d and CD5expression on CD19⁺ B220⁺ splenocytes from wild type and hCD19Tg micedoes not change following LPS, PMA, ionomycin, and monensin treatments,and permeabilization. CD1d and CD5 expression on CD19⁺ B220⁺ cellsbefore (thin line) or after 5 hour incubation with LPS, PMA, ionomycin,monensin, and permeabilization (thick line) was determined byimmunofluorescence staining with flow cytometry analysis. (B)IL-10-producing spleen B cells from wild type and hCD19Tg mice expressedboth CD1d and CD5. Purified CD19⁺ splenocytes were cultured with LPS,PMA, ionomycin, and monensin for 5 hours before permeabilization andstaining using CD1d, CD5, B220, and IL-10 mAbs, with four-color flowcytometry analysis. (C) Spleen IL-10-producing B cells represent aCD1d^(high)CD5⁺ subset distinct from B-1a cells in wild type and hCD19Tgmice. Histograms demonstrate cytoplasmic IL-10 expression bypermeabilized CD1d^(high)CD5⁺, CD1d^(low)CD5⁺, and CD1d⁻ CD5⁻ B cellsfrom wild type and hCD19Tg mice after LPS, PMA, and ionomycinstimulation. CD1d and CD5 expression by B cells from CD19^(−/−) andIL-10^(−/−) mice is also shown. Percentages indicate mean (±SEM)CD1d^(high)CD5⁺ cell, or IL-10⁺ cell frequencies among CD1d^(high)CD5⁺ Bcells as indicated for each group of three mice. (D) Stimulation doesnot induce the CD1d^(high)CD5⁺ phenotype of IL-10 secreting B cells.Splenic CD1d^(high)CD5⁺ or CD^(low)CD5⁻ B cells were purified from threewild type or hCD19Tg mice by cell sorting and pooled before LPS, PMA,and ionomycin stimulation for 5 h, with subsequent assessment forcytoplasmic IL-10 production by immunofluorescence staining. Percentagesindicate IL-10⁺ cell frequencies. (E) IgM, IgD, CD5, CD1d, CD21, CD24,CD23, CD11b, CD43, and B220 expression by IL-10⁺ (thick line) or IL-10⁻(dashed line) B cells from wild type and hCD19Tg mice. CD19⁺ splenocyteswere cultured with LPS, PMA, ionomycin, and monensin for 5 hours beforepermeabilization and staining for IL-10. Thin lines representisotype-matched control mAb staining. A-D). All results represent ≧2independent experiments with 3 mice in each group.

FIG. 6: IL-10 production by CD1d^(high)CD5⁺ B cells correlates withsuppression of T cell-mediated inflammation. (A) IL-10 production bywild type, hCD19Tg, and CD19^(−/−) B cells during CHS responses. B220⁺cells were purified from the spleen and draining lymph nodes of naivemice (filled bars) or 2 days following oxazolone challenge (open bars).(B) Splenic CD1d^(high)CD5⁺ or non-CD1d^(high)CD5⁺ B cells were purifiedfrom naïve or oxazolone challenged wild type mice (as in A) by cellsorting. (A, B) Values represent relative mean IL-10 transcriptsnormalized to GAPDH transcript levels (±SEM) in triplicate samples ofpooled RNA from 3 mice as quantified by real-time PCR analysis. Resultsare representative of at least 2 independent experiments with 3 mice ineach group. Significant differences between sample means are indicated;*p<0.05, **p<0.01. (C) CHS responses in hCD19Tg mice treated withanti-IL-10 receptor or isotype control mAb 1 hour before and 47 hoursafter oxazolone challenge. (D) CHS responses in wild type andIL-10^(−/−) mice after B cell depletion. Mice were treated with CD20 orisotype control mAb 7 days before the first sensitization withoxazolone. (C-D) Ear thickness was measured after oxazolone challenge asindicated. Values represent mean (±SEM) increases in ear thickness for≧4 mice of each group. Significant differences between the mean CHSresponses between groups and control mAb-treated wild type mice areindicated; *p<0.05; **p<0.01. (E) IL-10 production by circulating Bcells from wild type mice during CHS responses. Blood mononuclear cellsfrom three mice were pooled and cultured with LPS, PMA, ionomycin, andmonensin for 5 hours before the cells were stained with B220 and/or CD19or CD20 mAbs to identify B cells. After permeabilization, the cells werestained with anti-IL-10 mAb. Values represent the percentage ofIL-10-producing cells among total B cells with results from IL-10^(−/−)mice shown as a control.

FIG. 7: CD1d^(high)CD5⁺ B cells exert an inhibitory role during Tcell-mediated inflammatory responses. (A) Splenic CD1d^(high)CD5⁺ ornon-CD1d^(high)CD5⁺ B cells from sensitized or naive mice were purified(representative results, left panel). Purified cells from wild type(middle panel) or IL-10^(−/−) (right panel) mice were transferred intooxazolone-sensitized CD19^(−/−) mice. Recipient mice were challenged 48hours after transfer with increased ear thickness measured. Significantdifferences between mean CHS responses in control mice versus miceadoptively transferred with CD1d^(high)CD5⁺ B cells are indicated;*p<0.05. (B) CD1d^(high)CD5⁺ or non-CD1d^(high)CD5⁺ splenic B cells werepurified from sensitized or naive CD20^(−/−) mice and transferred intosensitized or naive wild type mice, respectively, that had been treatedwith CD20 or control mAb 7 days earlier using the same procedures as in(A). For sensitized mice, the adoptive transfer was performed 2 daysbefore challenge (middle panel). For naive mice, the adoptive transferwas performed 2 days before initial sensitization (right panel).Significant differences between CD20 mAb-treated control mice versusother groups are indicated; *p<0.05; **p<0.01. (C) Adoptive transfer ofCD1d^(high)CD5⁺ or non-CD1d^(high)CD5⁺ B cells purified fromDNFB-sensitized mice does not alter CHS responses in CD19−/− recipients.The same procedures were used as in (A) except the donor mice weresensitized with DNFB. A-C). Values represent means (±SEM) from ≧4 miceof each group.

FIG. 8: CD20 mAb-induced B cell depletion in EAE mice. Mice were treatedwith CD20 (closed bars) or control (open bars) mAb (250 μg) 7 daysbefore or 14 days after MOG immunization. Representative depletion of Bcells from the bone marrow (A), blood (B), spleen (C-E), peripherallymph nodes (F), and peritoneal cavity (G and H) on day 18. Bar graphsindicate the numbers of blood (per ml) and tissue B cells (mean±SEM,n≧4, *p<0.05, **p<0.01). Percentages indicated within the bar graphsrepresent relative B cell number in CD20 mAb-treated mice compared tocontrol mAb-treated littermates.

FIG. 9: B cells regulate EAE severity. Mide were treated with CD20(closed circles/bars) or control (open circles/bars) mAb (250 μg) 7 daysbefore or 14 days after MOG immunization. (A) Arrowheads indicate mAbinjection. Values represent EAE clinical scores (mean±SEM, n=10,*p<0.05). (B) Spinal cord tissues harvested on day 18 (mean±SEM, n≧4,*p<0.05). Arrowheads indicate focal demyelination. Originalmagnification: ×200. (C) B cell depletion attenuates MOG-specificantibody production on day 18 (peak phase) and day 28 (recovery phase).Dashed lines indicate mean values for unimmunized mice (n=6). *p<0.01,**p<0.001.

FIG. 10: B cells regulate MOG-specific CD4⁺ T cell expansion in vivo.Mice were treated with CD20 (closed bars) or control (open bars) mAb(250 μg) 7 days before or 14 days after MOG immunization. (A)CFSE-labeled TCR^(MOG) CD4⁺ T cells were transferred into mice on day17. Four days later, lymph node cells were analyzed for CFSE division(gated on CD4⁺Vβ11⁺CFSE⁺ cells). Bar graphs indicate the numbers ofdividing cells (mean±SEM, n≧4, *p<0.001). (B) CD4⁺ T cell subsets and(C) regulatory T cells (T-reg) on day 18 (mean±SEM, n≧4).

FIG. 11: B cells regulate CNS-infiltrating CD4⁺ T cell numbers andactivation during EAE. Mice were treated with CD20 (closed bars) orcontrol (open bars) mAb (250 tag) 7 days before or 14 days after MOGimmunization. (A) MOG-specific effector T cell (T-eff;MOG/IAb-tetramer⁺CD4⁺FoxP3⁻) and regulatory T cell (T-reg;MOG/IAb-tetramer⁺CD4⁺FoxP3⁺) on day 18. Bar graphs indicate the numbersand the ratio of T-eff/T-reg (mean±SEM, n≧4, *p<0.05). (B) IL-17 andIFN-γ production by CNS-infiltrating CD4⁺ T cells on day 18. Bar graphsindicate numbers of IL-17⁺ and IFN-γ⁺CD4⁺ T cells (mean±SEM, n≧4,*p<0.05, **p<0.01).

FIG. 12: Regulatory CD1d^(high)CD5⁺ B cells suppress disease symptoms inEAE. (A) Splenic CD19⁺ B cells from CD20^(−/−) mice, sorted intoregulatory CD1d^(high)CD5⁺ and non-regulatory CD1d^(high)CD5⁺ B cellsubsets. (B) CD1d^(high)CD5⁺ or non-CD1d^(high)CD5⁺ B cells (2×10⁶) fromCD20^(−/−) mice were transferred into wild type mice that had beentreated with CD20 or control mAb 5 days earlier (arrowhead). Recipientmice were immunized with MOG 2 days after transfer (day 0). Valuesrepresent EAE clinical scores (mean±SEM, n≧5). Significant differencesbetween mice treated with CD20 mAb versus CD20 mAb plus CD1d^(high)CD5⁺B cells: *p<0.05.

FIG. 13: CD40 stimulation induces IL-10 production by human and mouseblood B cells. Blood mononuclear cells were cultured with LPS, PMA,ionomycin, and monensin for 5 hours, or were cultured with CD40 mAb for48 hours with LPS, PMA, ionomycin, and monensin added during the final 5hours of culture. The cells were stained with CD19 mAb to identify Bcells. After permeabilization, the cells were stained with anti-IL-10mAb. Values represent the percentage of IL-10-producing cells amongtotal B cells and are representative of three independent experiments.

FIG. 14: IL-10 producing B cells in blood samples from healthy humandonors. Peripheral blood mononuclear cells (PBMC) were isolated fromfour healthy human donors and activated in vitro in RPMI 1640 mediacontaining 10% fetal bovine serum (FBS), 10 μg/ml of LPS, 50 ng/ml ofPMA, 500 ng/ml of ionomycin, and monensin for 5 hours. IL-10⁺ and IL-10⁻B cells were identified by immunofluorescence staining with flowcytometry analysis. The relative frequencies of IL-10⁺ cells in theindicated gates are shown, with background cytoplasmic staining shownfor an isotype control mAb.

FIG. 15: B cell depletion with CD20 mAb enhances the growth andmetastasis of melanoma tumors. A. Mice were treated with control mAb(open bars) or CD20 mAb (filled bars) seven days before subcutaneousinjection of B16 melanoma cells. Values represent the mean (±SEM) tumorvolume on the indicated day. B. Mice were treated with mAb as in (A),and injected intravenously with B16 melanoma cells. Values represent themean (±SEM) number of lung metastasis spots on the indicated day. A-B.Differences between sample values were statistically significant: *,p<0.05; **, p<0.01. C. Representative pictures of lungs from control andCD20 mAb-treated mice 14 days after receiving an intravenous injectionof B16 melanoma cells.

FIG. 16: Survival of lymphoma-bearing CD20 mAb-treated mice is enhancedwhen endogenous B cells are depleted. B6 wild type (A) or CD20^(−/−) (B)mice were injected subcutaneously with CD20⁺ syngeneic lymphoma cellsderived from a C57BL/6 Eμ-cMyc transgenic mouse on day 0, and thenreceived 250 μg of control or CD20 mAb on day 1 and day 7. Mice weremonitored daily for survival. C. Percent survival comparison betweenCD20 mAb-treated lymphoma-bearing B6 WT and CD20^(−/−) mice.

FIG. 17. B10 cells preferentially secrete IL-10. (A) IL-10-producing Bcells were predominantly found within the CD1d^(hi)CD5⁺CD19⁺ B cellsubset. Splenocytes from wild type and IL-10^(−/−) mice were culturedwith L+PIM for 5 h, then stained with CD1d, CD5, and CD19 mAb beforepermeabilization and staining using IL-10 mAb. Percentages and bargraphs indicate mean (±SEM) B cell subset frequencies and numbers amongCD19⁺ splenocytes or IL-10⁺ cell frequencies among the indicated B cellsubsets (a, CD1d^(hi)CD5⁻; b, CD1d^(hi)CD5⁺; c, CD1d^(lo)CD5⁻; d,CD1d^(lo)CD5⁺) from 3 mice as determined by flow cytometry analysis.Values significantly different from background frequencies or numbersfor IL-10^(−/−) mice are indicated: *, p<0.05; **, p<0.01. (B) CD21,CD23, CD24, CD43, and CD93 expression by IL-10-producing (thick line)and IL-10⁻ (thin line) CD19⁺ spleen B cells from wild type mice culturedwith L+PIM for 5 h, then stained for cell surface antigens beforepermeabilization and cytoplasmic IL-10 staining. Gray histogramsrepresent isotype-matched control mAb staining. Results arerepresentative of those obtained with B cells from ≧3 mice as determinedby flow cytometry analysis. (C) IL-10-producing B cells from hCD19Tgmice are predominantly found within the CD1d^(hi)CD5⁺CD19⁺ B cellsubset. Staining and analysis was as described in (A). (D)Representative isolation of IL-10-secreting B cells. Splenic B220⁺ cellspurified from three hCD19Tg mice were pooled and cultured with L+PI for5 hours before staining for CD19 and secreted IL-10 capture (leftpanel). Cytoplasmic IL-10⁺ and IL-10⁻ B cells were isolated by cellsorting using the indicated gates and subsequently reassessed for IL-10secretion and CD19 expression (right panels). (E) Cytokine geneexpression by IL-10-secreting and non-secreting B cells purified as in(D). Mean fold-differences (±SEM) in cytokine transcript levels(IL-10⁺/IL-10⁻ cells) from 3 independent experiments are shown. Valuesof 1 (dashed line) indicate no difference in cytokine expression betweenthe IL-10⁺ and IL-10⁻ B cells, with significant differences indicated:**, p<0.005.

FIG. 18. B10 cell development in neonatal and 2- or 6-mo-old wild typeB6 mice. (A) Representative CD1d and CD5 expression by CD19⁺ B cells.Splenocytes were stained with CD1d, CD5, and CD19 mAbs with flowcytometry analysis of cells. Results represent one mouse indicating thefrequency of CD1d^(hi)CD5⁺ B cells among total B cells within theindicated gates. Bar graphs indicate mean (±SEM) percentages and numbersof CD1d^(hi)CD5⁺ B cells in one of two independent experiments withthree mice in each group. (B) IL-10 production by B cells. Splenocyteswere cultured with L+PIM for 5 h, then stained with CD19 mAb to identifyB cells, permeabilized, and stained using IL-10 mAb with flow cytometryanalysis. Representative results demonstrate the frequency ofIL-10-producing cells among total CD19⁺ B cells within the indicatedgates. Bar graphs indicate mean (±SEM) percentages and numbers of Bcells that produced IL-10 in one of two independent experiments withthree mice in each group. (A, B) Significant differences between samplemeans are indicated: *p<0.05, **, p<0.01. (C) Representative CD1d andCD5 expression by IL-10⁺ or IL-10⁻ B cells from neonatal mice.Horizontal and vertical gates delineate background staining usingunreactive isotype-matched control mAbs.

FIG. 19. B10 cell development in T cell-deficient and gnotobiotic mice.(A) CD1d and CD5 expression by spleen CD19⁺ B cells from 2 mo-old wildtype and nude mice. Results represent one mouse indicating the frequencyof CD1d^(hi)CD5⁺ B cells within the indicated gates among total B cells.Bar graphs indicate mean (±SEM) percentages and numbers of CD1d^(hi)CD5⁺B cells in one of two independent experiments with three mice in eachgroup. (B) IL-10 production by B cells from wild type and nude mice.Splenocytes were cultured with L+PIM for 5 h, stained with CD19 mAb,permeabilized, and stained using IL-10 mAb with flow cytometry analysis.Representative results demonstrate the frequency of IL-10-producingcells within the indicated gates among total CD19⁺ B cells. Bar graphsindicate mean (±SEM) percentages and numbers of B cells that producedIL-10 in one of two independent experiments with three mice in eachgroup. (C) CD1d and CD5 expression by IL-10⁺ or IL-10⁻ B cells from wildtype and nude mice. Data are representative of 2 independent experimentswith three mice in each group. Horizontal and vertical gates delineatebackground staining using unreactive isotype-matched control mAbs. (D)The presence of T cells during in vitro cultures does not influence Bcell IL-10 production. Wild type splenocytes or purified B220⁺ B cellswere cultured with L+PIM for 5 h, then stained with CD19 mAb,permeabilized, and stained using IL-10 mAb with flow cytometry analysis.Representative results demonstrate the frequency of IL-10-producingcells within the indicated gates among total CD19⁺ B cells. Bar graphsindicate mean (±SEM) percentages and numbers of B cells that producedIL-10 in one of two independent experiments with three mice in eachgroup. (E) CD1d and CD5 expression by spleen CD19⁺ B cells from specificpathogen free (SPF) and gnotobiotic mice. Bar graphs indicate mean(±SEM) percentages and numbers of CD1d^(hi)CD5⁺ B cells in three mice.(F) IL-10 production by B cells from specific-pathogen-free (SPF) andgnotobiotic mice cultured as in (B). Bar graphs indicate mean (±SEM)percentages and numbers of B cells that produced IL-10 in three mice.(A, B, D-F) Significant differences between sample means are indicated:*p<0.05, **, p<0.01.

FIG. 20. Autoimmunity promotes B10 cell expansion. (A) CD1d and CD5expression by spleen B cells from 2 mo-old wild type B6, NZB/W F1,MRL/lpr, NOD, DBA/1, and SJL/J mice. Representative results demonstratethe frequency of CD1d^(hi)CD5⁺ B cells within the indicated gates amongtotal CD19⁺ B cells. Horizontal and vertical gates are set to delineatethe CD1d^(hi)CD5⁺ B cell subset. Bar graphs indicate mean (±SEM)percentages and numbers of CD1d^(hi)CD5⁺ B cells in one of twoindependent experiments with 3 mice in each group. (B) IL-10 productionby B cells. Splenocytes were cultured with L+PIM for 5 h, then stainedwith CD19 mAb, permeabilized, and stained using IL-10 mAb with flowcytometry analysis. Representative results demonstrate the frequency ofIL-10-producing cells within the indicated gates among total B cells.Bar graphs indicate mean (±SEM) percentages and numbers of B cells thatproduced IL-10 in one of two independent experiments with 3 mice in eachgroup. (A, B) Significant differences between sample means areindicated: *p<0.05, **, p<0.01. (C) CD1d and CD5 expression by IL-10⁺ orIL-10⁻ B cells. Horizontal and vertical gates are set to delineate theCD1d^(hi)CD5⁺ B cell subset as in (A). Data are representative of 2independent experiments with 3 mice in each group.

FIG. 21. Cell surface molecules that regulate B10 cell development invivo. (A) CD1d and CD5 expression by spleen B cells from wild type,IL-10^(−/−), MD4, CD19^(−/−), CD21^(−/−), CD40^(−/−), MHC-I/II^(−/−),MyD88^(−/−), hCD19Tg, CD22^(−/−), CD40L/BTg, and CD40L/BTg/CD22^(−/−)mice. Splenocytes were stained with CD1d, CD5, and CD19 or CD20 mAbs(for CD19^(−/−) mice). Representative results demonstrate the frequencyof CD1d^(hi)CD5⁺ B cells within the indicated gates among total CD19⁺ orCD20⁺ B cells. Bar graphs indicate mean (±SEM) percentages and numbersof CD1d^(hi)CD5⁺ B cells in one of two independent experiments with 3mice in each group. The horizontal dashed lirie is provided forreference to wild type mice. (B) IL-10 production by B cells.Splenocytes were cultured with L+PIM for 5 h, stained with CD19 or CD20mAb, permeabilized, and stained using IL-10 mAb with flow cytometryanalysis. Representative frequencies of IL-10-producing cells within theindicated gates among total CD19⁺ or CD20⁺ B cells. Bar graphs indicatemean (±SEM) percentages and numbers of B cells that produced IL-10 inone of two independent experiments with 3 mice in each group. Thehorizontal dashed line is for reference.

FIG. 22. In vitro B cell stimulation induces IL-10 production andsecretion. CD19⁺ splenocytes were purified from (A, B) wild type mice,or (C, D) wild type (filled bars) and MyD88^(−/−) (open bars)littermates. Purified B cells were cultured with media alone, LPS,L+PIM, agonistic CD40 mAb, mitogenic anti-IgM Ab, or variouscombinations of these stimuli for the times indicated. For cytoplasmicIL-10 staining, PIM was added as indicated during the last 5 hours ofall cultures before the cells were isolated, stained with CD19 mAb,permeabilized, and stained with IL-10 mAb for flow cytometry analysis.(A) Values within representative histograms indicate the percentage ofIL-10-producing cells within the gates shown among total B cells.Monensin was added for 5 hours to media-only and LPS-only cultures. (B,D) For measuring secreted IL-10, culture supernatant fluid was harvestedfrom cultured cells at the times indicated, with IL-10 concentrationsdetermined by ELISA. Bar graphs indicate mean (±SEM) percentages or meanIL-10 (±SEM) concentrations from (A, B) one of 3 independent experimentswith 3 mice in each group, or (C, D) one experiment with 3 mice in eachgroup. (A-D) Significant differences between sample means are indicated:*p<0.05, **, p<0.01.

FIG. 23. LPS and CD40 signals induce the maturation of B10 progenitorcells. LPS and CD40 mAb induce IL-10 production by (A) neonatal spleenor (B) adult blood B cells from wild type mice. (A-B) Cells werecultured with LPS, agonistic CD40 mAb, or both for the times indicated,with PIM added during the last 5 hours of each culture. The culturedcells were isolated, stained with CD19 mAb, permeabilized, and stainedusing IL-10 mAb with flow cytometry analysis. Values withinrepresentative histograms indicate the percentage of IL-10-producingcells among CD19⁺ B cells within the gates shown. Bar graphs indicatemean (±SEM) percentages of IL-10 producing B cells in one of twoindependent experiments with 3 mice in each group. Significantdifferences between sample means are indicated: *p<0.05, **, p<0.01. (C)CD40 stimulation induces B cell CD5 expression. Cell surface CD 1d andCD5 expression by wild type CD19⁺ cells was determined byimmunofluorescence staining. Neonatal splenocytes, or adult blood andspleen B cells were freshly isolated, or cultured for 48 hours with LPSor agonistic CD40 mAb (plus or minus LPS for the last 5 hours ofculture). Values indicate the percentage of CD1d^(hi)CD5⁺ B cells amongtotal B cells within the indicated gates. Single color histograms arerepresentative of two independent experiments with 3 mice in each group.

FIG. 24. Effect of LPS or CD40 ligation on IL-10 production,proliferation, and the phenotype of CD1d^(hi)CD5⁺ B cells. (A) LPS andCD40 mAb-induced cytoplasmic IL-10 production are restricted toCD1d^(hi)CD5⁺ B cells. CD1d^(hi)CD5⁺ or CD1d^(lo)CD5⁻ B220⁺ B cells werepurified from pooled splenocytes of three wild type mice by cell sortingand reassessed for CD1d and CD5 expression (middle panels). The purifiedB cell subsets were cultured with LPS or CD40 mAb for 48 h, with L+PIMadded for the last 5 hours of culture before permeabilization, stainingfor IL-10, and flow cytometry analysis (right panels). The frequenciesof IL-10⁺ cells among the sorted CD1d^(hi)CD5⁺ or CD1d^(lo)CD5⁻ B cellsubsets are shown for one of two independent experiments. (B) Clonalexpansion of IL-10-producing B cells after LPS but not CD40 stimulationin vitro for 48 h. Wild type CD19⁺ splenocytes were labeled with CFSEand cultured with LPS or CD40 mAb for 48 h, with L+PIM added for thelast 5 hours of culture. Histograms (right) represent CFSE expression bythe IL-10⁺ or IL-10 B cell subsets. Dashed lines represent CFSE stainingof unstimulated B cells. (A-B) Data are representative of 2 independentexperiments. (C) Potential B 10 developmental pathway leading to thegeneration of the IL-10 secreting B 10 cell subset. Dashed arrows andquestion marks represent potential maturation steps based on CD5 andCD1d expression patterns.

FIG. 25. B cell depletion enhances lymphoma killing by CD20 mAb in vivo.(a) CD20 and CD154 expression by primary BL3750 lymphoma cells. BL3750cells (thick line) and spleen B220⁺ cells from Eμ-cMycTG^(+/−) mice(thin line) were assessed by three-color immunofluorescence stainingwith flow cytometry analysis. Background staining using a control (CTRL)mAb is shown (dashed line). Results are representative of twoindependent experiments. (b) CD20^(−/−) mice are resistant to B celldepletion by CD20 mAb. Representative circulating IgM⁺B220⁺ B cells inwild type or CD20^(−/−) mice 6 days after CD20 mAb treatment. All micewere given 10⁶ BL3750 cells subcutaneously 1 day before mAb treatment.Identical results were obtained in mice not given tumor cells.Percentages indicate the relative frequencies of cells within the gates.Results are representative of four independent experiments. (c) B celldepletion prolongs overall mouse survival. Wild type or CD20^(−/−) micewere given 10⁵ (n=9-10 mice/group; left panels) or 10⁶ (n=10-18mice/group; right panels) BL3750 cells on day 0 with CD20 () or control(◯) mAb (250 μg/mouse) given on day 1 or days 1 and 7 (arrowheads) in ≧3independent experiments. Statistical comparisons of survival used theLog-Rank test. (d) Representative dorsal tumors resected from control orCD20 mAb-treated wild type or CD20^(−/−) mice 16 days after receiving10⁶ BL3750 cells. Line graphs indicate tumor volumes (±SEM) for wildtype or CD20^(−/−) mice given CD20 () or control (◯) mAb (250 μg/mouse)on days 1 and 7 following 10⁶ BL3750 cell transfer. Values representmean (±SEM) tumor volumes observed in 3-6 mice for each group from 2independent experiments. (e) Representative frequencies of IL-10producing B cells among total spleen CD19⁺ B cells in wild type mice orlittermates given 10⁵ BL3750 cells 28 days earlier, in comparison with Bcells from CD20^(−/−) and IL-10^(−/−) mice, and BL3750 cells. Bar graphsindicate mean (±SEM) percentages of IL-10⁺ cells among CD19⁺ B cells inwild type mice (open bars) or littermates given BL3750 cells (filledbars) either 14 or 28 days earlier, with three mice in each group. (d-e)Significant differences between means are indicated; *p<0.05, **p<0.01.

FIG. 26. Regulatory CD1d^(high)CD5⁺ B cells inhibit lymphoma killing byCD20 mAb in vivo through IL-10 dependent mechanisms. (a) Representativepurification of splenic CD19⁺ B cells from CD20^(−/−) mice intoCD1d^(high)CD5⁺ and non-CD1d^(high)CD5⁺ subsets. Percentages indicateIL-10⁺ cell frequencies among the indicated B cell subsets as determinedby flow cytometry analysis. (b) CD1d^(high)CD5⁺ B cells inhibitmacrophage activation in vivo. Wild type mice were untreated () orgiven CD1d^(high)CD5⁺ B cells from CD20^(−/−) mice (▪, 2×10⁶/mouse) oneday before CD20 mAb treatment. Spleen CD11b⁺F4/80⁺ macrophages wereisolated 18 and 48 hours after CD20 mAb treatment and assessed for MHCclass II (I-A/I-E) and CD86 expression by immunofluorescence staining.Graphs indicate an increase (%) in mean fluorescence stainingintensities relative to wild type mice treated with control mAb (dashedhorizontal line). Values represent individual mice, with horizontal barsindicating means. (c) CD1d^(high)CD5⁺ B cells inhibit lymphoma killingby CD20 mAb through IL-10 production. B cell subsets purified fromCD20^(−/−) or IL-10^(−/−) CD20^(−/−) mice were given to wild typerecipients (2×10⁶/mouse) one day before receiving 10⁶ BL3750 tumor cellson day 0. CD20 or control mAbs (250 μg/injection, arrowheads) were givenon days 1 and 7. Representative dorsal tumors were resected from mice onday 16. Tumor volumes (±SEM) and overall mouse survival were quantifiedafter tumor challenge and control (∘), CD20 mAb (), CD20 mAb plusCD1d^(high)CD5⁺ B cells (▪), or CD20 mAb plus non-CD1d^(high)CD5⁺ B cell(▴) treatments (n=10-18 mice/group) as indicated. Results representpooled data from 4 independent experiments. (b-c) Significantdifferences between means are indicated, *p<0.05, **p<0.01.

FIG. 27. Mouse CD20 Ab-mediated marginal zone B cell depletion isindependent of Fc receptor expression. A) Spleen follicular mature Bcell (FO-M, CD21⁺CD24⁺B220⁺) and marginal zone B cell (MZ-B,CD21^(high)CD1d^(high)B220⁺) numbers were determined 7 days after MB20-1IgG1, MB20-11 IgG2c, MB20-18 IgG2b, or isotype-matched control (CTL) mAbtreatment of C57BL/6 mice. B) Marginal zone B cell depletion in wildtype mice (open circles), FcγRI^(−/−) mice (open squares), FcγRIII^(−/−)mice (filled circles), and FcRγ^(−/−) mice (filled squares). Follicularmature B cell depletion in FcRγ^(−/−) mice is shown by filled diamonds.C) Marginal zone B cell depletion in wild type mice (open circles) andFcγRIIB^(−/−) mice (filled triangles). A-C) Values (±SEM) represent thepercentage of B cells present in CD20 mAb-treated mice (n=3) relative tocontrol mAb-treated littermates (n=3) at each mAb dose evaluated.Significant differences between sample means are indicated (*, p<0.05;**, p<0.01; f, p<0.01).

FIG. 28. Mouse CD20 mAb-mediated marginal zone B cell depletion iscomplement-independent pathway. A) Blood (B220⁺), spleen FO-M, andspleen MZ-B cell depletion in C3^(−/−) or C1q^(−/−) mice treated withMB20-11 CD20 mAb or control Ab (250 μg/mouse). Values (±SEM) indicatemean B cell numbers 7 days after mAb treatment (n=3). B) MB20-18 IgG2a(open squares) or MB20-18 IgG2a_(K322A) (filled squares) mAb depletionof FO-M and MZ-B cells in C57BL/6 (B6) and BUB mice. B cell numbers weredetermined 7 days after mAb treatment at the indicated mAb doses. Values(±SEM) represent percentages of B cells present in mAb-treated micerelative to control mAb treated littermates (n=3).

FIG. 29. Caspase-dependent apoptosis pathway is not involved in CD20mAb-mediated marginal zone B cell depletion. A) CD20 mAb alone did notinduce B cell apoptosis in vitro. Purified splenic B cells from wildtype mice cultured with control mAb (open triangles), MB20-11 mAb (opencircles), anti-IgM F(ab′)₂ Ab (open squares) or MB20-11 mAb plusanti-IgM F(ab′)₂ Ab (filled circles). After 12, 24, 36, and 72 hours,the cells were harvested and apoptotic cells were identified by annexinVand PI staining followed by FACS analysis. Histograms represent the dataobtained at 72 hours. These results are representative of threeexperiments. B-C) Blood and spleen FO-M and MZ-B cell numbers (±SEM)after MB20-11 (filled circles/bars) or isotype control (opencircles/bars) mAb treatment (250 μg/mouse) in Bcl-2 TG (n=3), Bcl-XLTG(n=4), B6^(lpr/lpr) (n=3), or TNF^(−/−) mice (n=5), or z-VAD.FMK-treatedC57BL/6 mice (n=3). Significant differences between sample means areindicated (*, p<0.05; **, p<0.01).

FIG. 30. Spleen FO-M, MZ-B and B10 cell (B220₊CD19₊IL10₊) numbers weredetermined 7 days after MB20-3 IgG3 mAb treatment at indicated Ab doses.Values (±SEM) represent the percentage of B cells present in mAb-treatedmouse (n=3) relative to control mAb-treated littermates (n=3).Significant differences between sample means are indicated (*, p<0.05;**, p<0.01; †, p<0.05; ††, p<0.01).

FIG. 31. A) Spleen FO-M and MZ-B cell numbers were determined in C57BL/6mice 7 days after MB20-3 (black bars), MB20-13 (grey bars), MB20-18(hatched bars), or control mAb (white bars) treatment (50 μg/mouse). B)Splenocytes from control, MB20-3, MB20-13, or MB20-18 mAb treatedC57BL/6 mice were stimulated with LPS, PMA, ionomycin, and monensin for5 hours. CD1d and CD5 expression on B220⁺ cells (upper panel) and thefrequencies of IL-10 producing B cells (lower panel) were determined byimmunofluorescence staining. Bar graphs indicated mean (±SEM)percentages and numbers of B cells that produced IL-10 in onerepresentative experiment with three mice per group. A-B) Significantdifferences between sample means are indicated (*,p<0.05; **, p<0.01).

FIG. 32. CD22 mAb depletes B10 cells. Eight week-old C57BL/6 mice weretreated with CD22 mAb (MB22-10; 250 μg/mouse) or control mAb (B1; 250μg/mouse) 7 days before analysis. (A) Representative CD1d and CD5expression by CD19₊ B cells. Splenocytes were stained with CD1d, CD5,and CD19 mAbs with flow cytometry analysis of viable cells. Resultsrepresent one mouse indicating the frequency of CD1 d_(hi)CD5₊ B cellsamong total B cells within the indicated gates. Bar graphs indicate mean(±SEM) percentages and numbers of CD1d_(hi)CD5₊ B cells in one of twoindependent experiments with three mice in each group. (B) IL-10production by B cells. Splenocytes were cultured with LPS (10 μg/ml),PMA (50 ng/ml), ionomycin (500 ng/ml), and monensin (2 μM) for 5 h, thenstained with B220 and CD19 mAb to identify B cells, permeabilized, andstained using IL-10 mAb with flow cytometry analysis of viable cells.Representative results demonstrate the frequency of IL-10-producingcells among total B220₊ B cells within the indicated gates. Bar graphsindicate mean (±SEM) percentages and numbers of B cells that producedIL-10 in one of two independent experiments with three mice in eachgroup. Leukocytes from IL-10_(−/−) mice served as negative controls todemonstrate specificity and to establish background IL-10 staininglevels. (A, B) Significant differences between sample means areindicated: **, p<0.01.

5. DETAILED DESCRIPTION

The present invention relates to a phenotypically distinctCD1d^(high)CD5⁺ B cell subset that regulates T cell mediatedinflammatory and immune responses through secretion of IL-10. Theinvention also relates to harnessing this regulatory B cell subset forthe manipulation of the immune and inflammatory responses, and for thetreatment of diseases, disorders and conditions associated with alteredIL-10 levels, including inflammatory and autoimmune diseases, as well asimmunosuppression and cancer in humans and other mammals.

Cellular compositions enriched for the CD1d^(high)CD5⁺ B cell subset,and methods for their preparation are described. These cellularcompositions can be expanded and used in adoptive transfer therapies totreat conditions associated with diminished IL-10 production, e.g.,inflammatory and/or autoimmune conditions or diseases. In an alternativeapproach, therapeutic regimens designed to expand the endogenouspopulation of the CD1d^(high)CD5⁺ B cell subset, or increase theirproduction of IL-10 can be used to treat inflammatory and/or autoimmuneconditions or diseases in subjects in need thereof. In this approach,antibodies that activate and/or stimulate expansion of the regulatory Bcell subset, or increase their production of IL-10 can be used.Expansion can be accomplished in vivo (e.g., by direct administration ofthe antibody or receptor agonist) or ex vivo (e.g., by activating thecells obtained from the subject and returning the activated cells to thesubject).

In another embodiment, methods are described for treating diseases,disorders and conditions associated with enhanced IL-10 production,e.g., conditions involving immunosuppression and certain cancers. Thesetherapeutic approaches involve depleting or ablating the endogenousCD1d^(high)CD5⁺ regulatory B cell subset, or inhibiting their productionof IL-10 in subjects in need thereof. In this approach, antibodies thatkill the regulatory B cell subset, or inhibit their proliferation ortheir production of IL-10 can be used.

In yet another embodiment, methods for identifying the regulatory B cellsubset in patients and/or patient samples are described for diagnosingthe immune status of affected individuals.

In another embodiment, a method for generating an antibody thatpreferentially or selectively depletes the regulatory B cell populationis provided, the method comprising: (i) selecting an antibody that bindsto a marker that is presently known or subsequently determined to beexpressed by regulatory B cells including, e.g. CD5, CD19, CD20, CD21,CD22, CD24, CD40 and CD72; (ii) assaying the antibody for the ability toinduce homotypic adhesion of B cells (Kansas G S, Wood G S, Tedder T F.Expression, distribution and biochemistry of human CD39: Role inactivation-associated homotypic adhesion of lymphocytes. J. Immunol.1991; 146:2235-2244.; Kansas G S, Tedder T F. Transmembrane signalsgenerated through MHC class II, CD19, CD20, CD39 and CD40 antigensinduce LFA-1-dependent and -independent adhesion in human B cellsthrough a tyrosine kinase-dependent pathway. J. Immunol. 1991; 147:4094-4102.; Wagner N, Engel P, Vega M, Tedder T F. Ligation of MHC classI and class II molecules leads to heterologous desensitization of signaltransduction pathways that regulate homotypic adhesion in humanlymphocytes. J. Immunol. 1994; 152:5275-5287.); (iii) assaying theantibody for the ability to deplete the regulatory B cell population;and (iv) if needed, modifying the Fc region of the antibody so that themechanism of depletion of the regulatory B cell population by theantibody is independent of the antibody's Fc region.

5.1 The Regulatory B Cell Subset

The present invention relates to a regulatory subset of the normal Bcell population characterized phenotypically as CD1d^(high)CD5⁺, andfunctionally by its ability to produce IL-10. The invention also relatesto therapeutic uses of this regulatory B cell population.

The regulatory B cell phenotype can be determined by antibody stainingand flow cytometry, FACS, using antibodies to CD1d and CD5 andtechniques known in the art, including but not limited to thosedescribed in the examples, infra. See, e.g., Section 6 et seq. Theinvention is based, in part, on the surprising discovery that cellularcompositions enriched by selection for both CD1d^(high) and CD5 cellularmarkers will contain a high percentage of IL-10 producing B cells than apopulation enriched with only one of these markers.

The ability of the cells to produce IL-10 can be assessed by measuringIL-10 production in naive cells and in cultured cells stimulated withLPS (lipopolysaccharide), PMA (phorbol 12-myristate 13-acetate),ionomycin, CpG or comparable stimulatory Toll-like receptor agonists, orwith an agonist of CD40 (e.g., using an antibody to CD40). Production ofIL-10 by the cells can be assessed by assaying for IL-10 in the cellculture supernatant. In addition, production of IL-10 can be verifieddirectly by intracellular cytokine staining. Standard immunoassays knownin the art can be used for such purpose. Examples of assays for IL-10production are described in Section 6, infra. While IL-10 is produced atlow levels in the naive CD1d^(high)CD5⁺ B cell subset, IL-10 productionis increased in response to stimulation.

5.1.1 Cellular Compositions Enriched in the Regulatory B Cell Subset

The enriched, isolated and/or purified regulatory B cell subsetcomposition can comprise anywhere from 0.5% to 50%, at least 55%, atleast 60%, at least 65%, at least 70%, at least 75%, at least 80%, atleast 85%, at least 90%, at least 95%, at least 99%, or 100% regulatoryB cells having the CD1d^(high)CD5⁺ phenotype that produce IL-10 (asdetermined by the assays described above). In a preferred embodiment,the enriched/purified regulatory B cell subset comprises greater than50% regulatory B cells having the CD1d^(high)CD5⁺ phenotype. In a morepreferred embodiment, the enriched/purified regulatory B cell subsetcomprises greater than 75% regulatory B cells having the CD1d^(high)CD5⁺phenotype. In a still more preferred embodiment, the enriched/purifiedregulatory B cell subset comprises greater than 90% regulatory B cellshaving the CD1d^(high)CD5⁺ phenotype.

The enriched, isolated and/or purified CD1d^(high)CD5⁺ regulatory Bcells can be obtained from a mammalian subject, including but notlimited to rodents, e.g. mice, rats; livestock, e.g. pigs, horses, cows,etc., pets, e.g. dogs, cats; and primates, e.g. humans. In oneembodiment, the subject is an animal model of an IL-10 associateddisease. The phenotypic markers described herein were identified inmurine models; however, the invention contemplates that the cognatehuman regulatory B cell population will also produce IL-10, will bephenotypically distinct from other B cell populations, and will likelyutilize the same transcription factors and display the same cell surfacemarkers.

Alternatively, the regulatory B cells may be enriched/purified from anytissue where they reside including, but not limited to, blood (includingblood collected by blood banks), spleen, bone marrow, tissues removedand/or exposed during surgical procedures, and tissues obtained viabiopsy procedures. Tissues/organs from which the regulatory B cells areenriched, isolated, and/or purified may be isolated from both living andnon-living subjects, wherein the non-living subjects are organ donors.

Methods for the isolation of the regulatory B cells are based onselecting cells having the CD1d^(high)CD5⁺ cell-specific markers;however, additional markers can be included for selection, such asCD19^(high). In a particular aspect of this embodiment, a population ofregulatory B cells is enriched/purified by flow cytometry asdemonstrated in the examples described in Section 6, infra. However, avariety of cell separation techniques known in the art can be used,including but not limited to magnetic separation using antibody-coatedmagnetic beads and/or particles, FACS, affinity chromatography, affinitycolumn separation, “panning” with antibody attached to a solid matrix,density gradient centrifugation, and counter-flow centrifugalelutriation. (See, e.g., Kumar and Lykke, 1984, Pathology, 1:53-62).

According to these embodiments, a cellular composition enriched for theCD1d^(high)CD5⁺ B cell subset that has been enriched by selection usingboth CD1d^(high) and CD5 as cellular markers will contain a higherpercentage of IL-10 producing B cells than one enriched using only oneof these markers. The use of the CD1d^(high) and CD5 markers toisolate/enrich/purify regulatory B cells that produce IL-10 has severaladvantages. Using these cell surface markers, as opposed tointracellular IL-10 as a marker, allows for the selection/sorting of theIL-10 producing B cell population without permeabilizing the cells,which would make them therapeutically useless.

Regulatory B cells can also be isolated by negatively selecting againstcells that are not regulatory B cells. This can be accomplished byperforming a lineage depletion, wherein cells are labeled withantibodies for particular lineages such as the T lineage, themacrophage/monocyte lineage, the dendritic cell lineage, the granulocytelineages, the erythrocytes lineages, the megakaryocytes lineages, andthe like. Cells labeled with one or more lineage specific antibodies canthen be removed either by affinity column processing (where the lineagemarker positive cells are retained on the column), by affinity magneticbeads or particles (where the lineage marker positive cells areattracted to the separating magnet), by “panning” (where the lineagemarker positive cells remain attached to the secondary antibody coatedsurface), or by complement-mediated lysis (where the lineage markerpositive cells are lysed in the presence of complement by virtue of theantibodies bound to their cell surface). Another lineage depletionstrategy involves tetrameric complex formation. Cells are isolated usingtetrameric anti-human antibody complexes (e.g., complexes specific formultiple markers on multiple cell types that are not markers ofregulatory B cells, given in more detail infra) and magnetic colloid inconjunction with StemSep columns (Stem Cell Technologies, Vancouver,Canada). The cells can then optionally be subjected to centrifugation toseparate cells having tetrameric complexes bound thereto from all othercells.

In a certain embodiment, the enriched/purified population of regulatoryB cells can be stored for a future use. In this regard, the regulatory Bcell population can be stored by “cryopreservation.” Cryopreservation isa process where cells or whole tissues are preserved by cooling to lowsub-zero temperatures, such as 77 K or −196° C. in the presence of acryoprotectant. At these low temperatures, any biological activity,including the biochemical reactions that would lead to cell death, iseffectively stopped. Storage by cryopreservation includes, but is notlimited to, storage in liquid nitrogen, storage in freezers maintainedat a constant temperature of 0° C., storage in freezers maintained at aconstant temperature of −20° C., storage in freezers maintained at aconstant temperature of −80° C., and storage in freezers maintained at aconstant temperature of lower than −80° C. In one aspect of thisembodiment, the cells may be “flash-frozen,” e.g., in ethanol/dry ice orin liquid nitrogen prior to storage. In another aspect of thisembodiment, the cells can be preserved in medium comprising acryprotectant including, but not limited to dimethyl sulfoxide (DMSO),glycerol, ethylene glycol, propylene glycol, sucrose, and trehalose.Other methods of storing biological matter are well known to those ofskill in the art, such as “hibernation,” wherein cells are stored attemperatures above freezing or by preservation of the cells in a“static” state, as described in U.S. patent application publication No.2007/0078113, herein incorporated by reference in is entirety.

The population of regulatory B cells can be obtained from a subject inneed of therapy or suffering from a disease associated with elevated ordiminished levels of IL-10. Alternatively, the population of regulatoryB cells can be obtained from a donor, preferably a histocompatibilitymatched donor. The regulatory B cell population may be harvested fromthe peripheral blood, bone marrow, spleen, or any other organ/tissue inwhich regulatory B cells reside in said subject or donor. In a furtheraspect, the regulatory B cells may be isolated from a pool of subjectsand/or donors, or from pooled blood.

When the population of regulatory B cells is obtained from a donordistinct from the subject, the donor is preferably syngeneic, but canalso be allogeneic, or even xenogeneic, provided the cells obtained aresubject-compatible in that they can be introduced into the subject.Allogeneic donor cells are preferably human-leukocyte-antigen(HLA)-compatible, and are typically administered in conjunction withimmunosuppressive therapy. To be rendered subject-compatible, xenogeneiccells may be subject to gamma irradiation or PEN110 treatment asdescribed (Fast et al., 2004, Transfusion 44:282-5).

5.1.2. Enrichment of the Regulatory B Cell Subset

Regulatory B cells can be enriched by selecting cells having theCD1d^(high)CD5⁺ surface markers and separating using automated cellsorting such as fluorescence-activated cell sorting (FACS), solid-phasemagnetic beads, etc. as demonstrated in examples described in sections 6and 7 infra. To enhance enrichment, positive selection may be combinedwith negative selection; i.e., by removing cells having surface markersspecific to non-B cells and/or those specific to non-regulatory B cells.Non-limiting examples of methods of negative selection are describedsupra. Exemplary surface markers specific to non-regulatory B cellsinclude CD3, CD4, CD7, CD8, CD15, CD16, CD34, CD56, CD57, CD64, CD94,CD116, CD134, CD157, CD163, CD208, F4/80, Gr-1, and TCR.

5.2 Expansion of the Regulatory B Cell Subset and/or Enhancing theirProduction of IL-10

In a particular embodiment, expansion of the regulatory B cellpopulation is achieved by contacting the population of regulatory Bcells with stimulatory composition sufficient to cause an increase inthe number of regulatory B cells. This may be accomplished by contactingthe enriched, isolated and/or purified B cell subset with a mitogen,cytokine, growth factor, or antibody. The regulatory B cells arepreferably expanded at least 10-fold and preferably at least 50, 100,200, 300, 500, 800, 1000, 10,000, or 100,000-fold. In a specific aspectof this embodiment, the expanded regulatory B cell population retainsall of the genotypic, phenotypic, and functional characteristics of theoriginal population. In another embodiment, one or more of thecharacteristics of the regulatory B cell population is lost or modifiedfollowing expansion.

Levels of IL-10 produced by the regulatory B cell subset can beincreased by administration of agonists to the B cell surface receptorCD40. Non-limiting examples of CD40 agonists include anti-CD40antibodies and fragments thereof, the CD40 ligand and polypeptidefragments thereof, small molecules, synthetic drugs, peptides (includingcyclic peptides), polypeptides, proteins, nucleic acids, synthetic ornatural inorganic molecules, mimetic agents, and synthetic or naturalorganic molecules.

In a certain embodiment, the CD40 agonist is an anti-CD40 antibody. Theanti-CD40 antibodies of the invention can be of any form, as disclosedabove. Antibodies to CD40 are known in the art (see, e.g., Buhtoiarov etal., 2005, J. Immunol. 174:6013-22; Francisco et al., 2000, Cancer Res.60:3225-31; Schwulst et al., 2006, 177:557-65, herein incorporated byreference in their entireties).

Expansion of IL-10 production by the regulatory B cell subset can beadvantageously achieved ex vivo, i.e., by isolating the enrichedCD1d^(high)CD5⁺ population and contacting the cells with a CD40 agonist.In an aspect of this embodiment, the cells are contacted with a CD40agonist and relevant antigen(s). In a specific aspect of thisembodiment, the cells are contacted with both an anti-CD40 antibody andrelevant antigen(s).

5.3 Ablation of the Regulatory B Cell Subset and/or Inhibiting theirProduction of IL-10

The regulatory B cell subset can be ablated by engaging the B cellsurface receptor CD22. Non-limiting examples of compounds capable ofengaging CD22 to ablate the regulatory B cell population includeanti-CD22 antibodies and fragments thereof, the CD22 ligand andfragments thereof, CD22 ligand mimetics, small molecules, syntheticdrugs, peptides (including cyclic peptides), polypeptides, proteins,nucleic acids, synthetic or natural inorganic molecules, mimetic agents,and synthetic or natural organic molecules. Antibodies to CD22 are knownin the art (see, e.g., Tuscano et al., 2003, Blood 101:3641-7; US2004/0001828 A 1; and US 2007/0264360, incorporated by reference hereinin their entireties).

Alternatively, a bispecific antibody for CD1d and CD5 may be used totarget the regulatory B cell subset (these will be referred to herein asbispecific “anti-CD1d/CD5”). Bispecific antibodies can be prepared fromanti-CD1d and anti-CD5 antibodies using techniques that are known in theart (see, e.g., U.S. Pat. Nos. 5,534,254, 5,837,242, 6,492,123; U.S.Patent application publication Nos. 20040058400 and 20030162709, whichare all herein incorporated by reference in their entireties).

In order to kill or ablate the regulatory B cell subset, targetingantibodies (e.g., anti-CD22 or bispecific anti-CD1d/CD5) of an isotypethat mediate ADCC (antibody-dependent and mediated toxicity) or CDC(complement-dependent cytotoxicity) can be used. Of the various humanimmunoglobulin classes, IgG1, IgG2, IgG3, IgG4 and IgM are known toactivate complement. Human IgG1 and IgG3 are known to mediate ADCC.

Antibodies targeting the CD1d^(high)CD5⁺ regulatory B cell subset can befurther conjugated to a cytotoxic agent, using methods known in the art(see, e.g., DiJoseph et al., 2004, Clin. Cancer Res. 10:8620-9). Thismay be preferred when using antibodies or antibody fragments that do notmediate ADCC or CDC. Non-limiting examples of cytotoxic agents includeantimetabolites (e.g., cytosine arabinoside, aminopterin, methotrexate,6-mercaptopurine, 6-thioguanine, cytarabine, and 5-fluorouracildecarbazine); alkylating agents (e.g., mechlorethamine, thiotepachlorambucil, melphalan, carmustine (BCNU) and lomustine (CCNU),cyclophosphamide, busulfan, dibromomannitol, streptozotocin, mitomycinC, cis-dichlorodiammine-platinum (II) (CDDP), and cisplatin); vincaalkaloid; anthracyclines (e.g., daunorubicin (formerly daunomycin) anddoxorubicin); antibiotics (e.g., dactinomycin (formerly actinomycin),bleomycin, mithramycin, and anthramycin (AMC)); calicheamicin; CC-1065and derivatives thereof; auristatin molecules (e.g., auristatin PHE,bryostatin-1, and dolastatin-10; see Woyke et al., Antimicrob. AgentsChemother. 46:3802-8 (2002), Woyke et al., Antimicrob. Agents Chemother.45:3580-4 (2001), Mohammad et al., Anticancer Drugs 12:735-40 (2001),Wall et al., Biochem. Biophys. Res. Commun. 266:76-80 (1999), Mohammad,et al., Int. J. Oncol. 15:367-72 (1999), all of which are incorporatedby reference herein in their entireties); DNA-repair enzyme inhibitors(e.g., etoposide or topotecan); kinase inhibitors (e.g., compoundST1571, imatinib mesylate (Kantarjian et al., Clin. Cancer Res.8(7):2167-76 (2002)); demecolcine; and other cytotoxic agents (e.g.,paclitaxel, cytochalasin B, gramicidin D, ethidium bromide, emetine,mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicine,doxorubicin, daunorubicin, dihydroxy anthracenedione, mitoxantrone,mithramycin, actinomycin D, 1-dehydrotestosterone, glucorticoids,procaine, tetracaine, lidocaine, propranolol, and puromycin and analogsor homologues thereof and those compounds disclosed in U.S. Pat. Nos.6,245,759, 6,399,633, 6,383,790, 6,335,156, 6,271,242, 6,242,196,6,218,410, 6,218,372, 6,057,300, 6,034,053, 5,985,877, 5,958,769,5,925,376, 5,922,844, 5,911,995, 5,872,223, 5,863,904, 5,840,745,5,728,868, 5,648,239, 5,587,459, all of which are incorporated byreference herein in their entirety); farnesyl transferase inhibitors(e.g., R115777, BMS-214662, and those disclosed by, for example, U.S.Pat. Nos. 6,458,935, 6,451,812, 6,440,974, 6,436,960, 6,432,959,6,420,387, 6,414,145, 6,410,541, 6,410,539, 6,403,581; 6,399,615,6,387,905, 6,372,747, 6,369,034, 6,362,188, 6,342,765, 6,342,487,6,300,501, 6,268,363, 6,265,422, 6,248,756, 6,239,140, 6,232,338,6,228,865, 6,228,856, 6,225,322, 6,218,406, 6,211,193, 6,187,786,6,169,096, 6,159,984, 6,143,766, 6,133,303, 6,127,366, 6,124,465,6,124,295, 6,103,723, 6,093,737, 6,090,948, 6,080,870, 6,077,853,6,071,935, 6,066,738, 6,063,930, 6,054,466, 6,051,582, 6,051,574, and6,040,305, all of which are herein incorporated by reference in theirentirety); topoisomerase inhibitors (e.g., camptothecin, irinotecan,SN-38, topotecan, 9-aminocamptothecin, GG211 (GI147211), DX-8951f,IST-622, rubitecan, pyrazoloacridine, XR5000, saintopin, UCE6, UCE1022,TAN-1518A, TAN 1518B, KT6006, KT6528, ED-110, NB-506, ED-110, NB-506,and rebeccamycin); bulgarein; DNA minor groove binders such as Hoechstdye 33342 and Hoechst dye 33258; nitidine; fagaronine; epiberberine;coralyne; beta-lapachone; BC-4-1; antisense oligonucleotides (e.g.,those disclosed in the U.S. Pat. Nos. 6,277,832, 5,998,596, 5,885,834,5,734,033, and 5,618,709, all of which are herein incorporated byreference in their entirety); adenosine deaminase inhibitors (e.g.,fludarabine phosphate and 2-chlorodeoxyadenosine); and pharmaceuticallyacceptable salts, solvates, clathrates, and prodrugs thereof.

In another embodiment, the anti-CD22 or bispecific anti-CD1d/CD5antibody can be conjugated to a radioactive metal ion, such as thealpha-emitters ²¹¹astatine, ²¹²bismuth, ²¹³bismuth; the beta-emitters¹³¹iodine, ⁹⁰yttrium, ¹⁷⁷lutetium, ¹⁵³samarium, and ¹⁰⁹palladium; ormacrocyclic chelators useful for conjugating radiometal ions, includingbut not limited to, ¹³¹indium, ¹³¹L, ¹³¹yttrium, ¹³¹holmium,¹³¹samarium, to polypeptides or any of those listed supra. In certainembodiments, the macrocyclic chelator is1,4,7,10-tetraazacyclododecane-N,N′,N″,N″-tetraacetic acid (DOTA), whichcan be attached to the antibody via a linker molecule. Such linkermolecules are commonly known in the art and described in Denardo, etal., 1998, Clin Cancer Res 4(10):2483-90; Peterson, et al., 1999,Bioconjug Chem 10(4):553-7; and Zimmerman, et al., 1999, Nucl Med Biol26(8):943-50, each incorporated by reference herein in their entireties.

In still another embodiment, the anti-CD22 antibody or bispecificanti-CD1d/CD5 antibody is conjugated to a proteinaceous agent thatmodifies a given biological response and leads to cytotoxicity. In oneembodiment, the antibody is conjugated to a plant-, fungus-, orbacteria-derived toxin. Non-limiting examples of such toxins include Achain toxins, ribosome inactivating proteins, ricin A, deglycosylatedricin A chain, abrin, alpha sarcin, aspergillin, restrictocin,ribonucleases, diphtheria toxin, bacterial endotoxin, saporin toxin,Granzyme B or the lipid A moiety of bacterial endotoxin, cholera toxin,or Pseudomonas exotoxin and derivatives and variants thereof.

In another embodiment, an antagonist capable of engaging CD22 to ablatethe regulatory B cell population is a synthetic CD22 ligand, such asthat described in Collins et al., 2006, J. Immunol. 5:2994-3003,incorporated herein by reference in its entirety. In one aspect of thisembodiment, the synthetic CD22 ligand may be further conjugated to atoxin, such as the saporin toxin.

Alternatively, a compound capable of engaging a marker or markers on theregulatory B cell subset can inhibit the production of IL-10 by theregulatory B cells. Non-limiting examples of such compounds includeantibodies and fragments thereof, small molecules, synthetic drugs,peptides (including cyclic peptides), polypeptides, proteins, nucleicacids, synthetic or natural inorganic molecules, mimetic agents, andsynthetic or natural organic molecules. In one embodiment, the compoundengages CD22. In an aspect of this embodiment, the compound is ananti-CD22 antibody. In another aspect of this embodiment, the compoundengages CD5. In an aspect of this embodiment, the compound is ananti-CD5 antibody. In another aspect of this embodiment, the compoundengages CD1d. In an aspect of this embodiment, the compound is ananti-CD1d antibody. In still another aspect of this embodiment, thecompound is a bispecific anti-CD1d/CD5 antibody. In yet another aspectof this embodiment, the compotind engages CD19. In an aspect of thisembodiment, the compound is an anti-CD19 antibody.

5.4 Production of Therapeutic Antibodies

Antibodies that target, activate, inhibit and/or kill the regulatory Bcell CD1d^(high)CD5⁺ subset and which can be used in the therapeuticregimens described herein can be made using techniques well known in theart. The practice of the invention employs, unless otherwise indicated,conventional techniques in molecular biology, microbiology, geneticanalysis, recombinant DNA, organic chemistry, biochemistry, PCR,oligonucleotide synthesis and modification, nucleic acid hybridization,and related fields within the skill of the art. These techniques aredescribed in the references cited herein and are fully explained in theliterature. See, e.g., Sambrook et al, 2001, Molecular Cloning: ALaboratory Manual, Cold Spring Harbor Laboratory Press, Cold SpringHarbor, N.Y.; Ausubel et al, Current Protocols in Molecular Biology,John Wiley &Sons (1987 and annual updates); Current Protocols inImmunology, John Wiley & Sons (1987 and annual updates) Gait (ed.)(1984) Oligonucleotide Synthesis: A Practical Approach, IRL Press;Eckstein (ed.) (1991) Oligonucleotides and Analogues: A PracticalApproach, IRL Press; Birren et al (eds.) (1999) Genome Analysis: ALaboratory Manual, Cold Spring Harbor Laboratory Press, each of which isincorporated by reference herein in its entirety.

Antibodies for use in the methods of the invention include, but are notlimited to, synthetic antibodies, monoclonal antibodies (mAbs),recombinantly produced antibodies, multispecific antibodies (includingbi-specific antibodies), human antibodies, humanized antibodies,chimeric antibodies, intrabodies, diabodies, single-chain Fvs (scFv)(e.g., including monospecific, bispecific, etc.), camelized antibodies,Fab fragments, F(ab′) fragments, disulfide-linked Fvs (sdFv),anti-idiotypic (anti-Id) antibodies, and epitope-binding fragments ofany of the above.

In particular, antibodies to be used in the methods of the inventioninclude immunoglobulin molecules and immunologically active portions ofimmunoglobulin molecules, i.e., molecules that contain an antigenbinding site that binds to a CD22 or CD40 antigen, or bispecifically tothe CD1d and CD5 antigens. The immunoglobulin molecules can be of anytype (e.g., IgG, IgE, IgM, IgD, IgA and IgY), class (e.g., IgG1, IgG2,IgG3, IgG4, IgA1 and IgA2) or subclass of immunoglobulin molecule.

Variants and derivatives of antibodies include antibody fragments thatretain the ability to specifically bind to an epitope. In certainembodiments, fragments include Fab fragments; Fab′; F(ab′)₂; abispecific Fab; a single chain Fab chain comprising a variable region,also known as, a sFv; a disulfide-linked Fv, or dsFv; a camelized VH; abispecific sFv; a diabody; and a triabody. Derivatives of antibodiesalso include one or more CDR sequences of an antibody combining site. Incertain embodiments, the antibody to be used with the inventioncomprises a single-chain Fv (“scFv”).

The antibodies used in the methods of the invention may be from anyanimal origin including birds and mammals (e.g., human, murine, donkey,sheep, rabbit, goat, guinea pig, camel, horse, or chicken).

In certain embodiments, the antibodies of the invention are monoclonalantibodies (mAbs). Monoclonal antibodies can be prepared using a widevariety of techniques known in the art including the use of hybridoma,recombinant, and phage display technologies, or a combination thereof.For example, mAbs can be produced using hybridoma techniques includingthose known in the art and taught, for example, in Harlow et al.,Antibodies: A Laboratory Manual, (Cold Spring Harbor Laboratory Press,2nd ed. 1988); Hammerling et al., in: Monoclonal Antibodies and T-CellHybridomas 563 681 (Elsevier, N.Y., 1981) (each of which is hereinincorporated by reference in their entireties).

Antibodies can also be generated using various phage display methods.Examples of phage display methods that can be used to make theantibodies include those disclosed in Brinkman et al., 1995, J. Immunol.Methods 182:41-50; Ames et al., 1995, J. Immunol. Methods 184:177-186;Kettleborough et al., 1994, Eur. J. Immunol. 24:952-958; Persic et al,1997, Gene 187:9-18; Burton et al., 1994, Advances in Immunology57:191-280; PCT Application No. PCT/GB91/O1 134; InternationalPublication Nos. WO 90/02809, WO 91/10737, WO 92/01047, WO 92/18619, WO93/1 1236, WO 95/15982, WO 95/20401, and WO97/13844; and U.S. Pat. Nos.5,698,426, 5,223,409, 5,403,484, 5,580,717, 5,427,908, 5,750,753,5,821,047, 5,571,698, 5,427,908, 5,516,637, 5,780,225, 5,658,727,5,733,743 and 5,969,108; each of which is incorporated by referenceherein in its entirety.

In certain embodiments, the antibodies of the invention are chimericantibodies or single chain antibodies. Techniques developed for theproduction of “chimeric antibodies” (Morrison et al., 1984, Proc NatlAcad Sci 81:851; Neuberger et al., 1984 Nature 312:604; Takeda et al.,1985, Nature 314:452, each incorporated by reference herein in itsentirety) and single chain antibodies (U.S. Pat. No. 4,946,778; Bird,1988, Science 242:423; Huston et al, 1988, Proc Natl Acad Sci USA85:5879; and Ward et al, 1989, Nature 334:544, each incorporated byreference herein in its entirety) are well known in the art.

In a certain embodiment, antibodies used in the methods of the inventionare humanized antibodies. Humanized antibodies can be produced usingvariety of techniques known in the art, including but not limited to,CDR-grafting (European Patent No. EP 239,400; International publicationNo. WO 91/09967; and U.S. Pat. Nos. 5,225,539, 5,530,101, and 5,585,089,each of which is herein incorporated by reference in its entirety),veneering or resurfacing (European Patent Nos. EP 592,106 and EP519,596; Padlan, 1991, Molecular Immunology 28(4/5):489-498; Studnickaet al., 1994, Protein Engineering 7(6):805-814; and Roguska et al, 1994,PNAS 91:969-973, each of which is incorporated by reference herein inits entirety), chain shuffling (U.S. Pat. No. 5,565,332, hereinincorporated by reference in its entirety), and techniques disclosed in,e.g., U.S. Pat. No. 6,407,213, U.S. Pat. No. 5,766,886, WO 9317105, Tanet al., 2002, J. Immunol. 169:1119 25, Caldas et al., 2000 Protein Eng.13(5):353-60, Morea et al., 2000, Methods 20(3):267 79, Baca et al.,1997, J. Biol. Chem. 272(16):10678-84, Roguska et al., 1996, ProteinEng. 9(10):895 904, Couto et al., 1995 Cancer Res. 55 (23Supp):5973s-5977s, Couto et al., 1995, Cancer Res. 55(8):1717-22, SandhuJ S, 1994, Gene 150(2):409-10, and Pedersen et al., 1994, J. Mol. Biol.235(3):959-73 U.S. Patent Pub. No. US 2005/0042664 A1 (Feb. 24, 2005),each of which is incorporated by reference herein in its entirety.Often, framework residues in the framework regions will be substitutedwith the corresponding residue from the CDR donor antibody to alter,preferably improve, antigen binding. These framework substitutions areidentified by methods well known in the art, e.g., by modeling of theinteractions of the CDR and framework residues to identify frameworkresidues important for antigen binding and sequence comparison toidentify unusual framework residues at particular positions. (See, e.g.,Queen et al., U.S. Pat. No. 5,585,089; and Reichmann et al., 1988,Nature 332:323, each of which is incorporated by reference herein in itsentirety).

Single domain antibodies can be produced by methods well-known in theart. (See, e.g., Riechmann et al., 1999, J. Immunol. 231:25-38; Nuttallet al., 2000, Curr. Pharm. Biotechnol. 1(3):253-263; Muylderman, 2001,J. Biotechnol. 74(4):277302; U.S. Pat. No. 6,005,079; and InternationalPublication Nos. WO 94/04678, WO 94/25591, and WO 01/44301, each ofwhich is incorporated herein by reference in its entirety).

Further, antibodies that bind to a desired antigen can, in turn, beutilized to generate anti-idiotype antibodies that “mimic” an antigenusing techniques well known to those skilled in the art. (See, e.g.,Greenspan & Bona, 1989, FASEB J. 7(5):437-444; and Nissinoff, 1991, J.Immunol. 147(8):2429-2438, herein incorporated by reference in theirentireties).

Bispecific antibodies can be prepared using techniques that are known inthe art. (See, e.g., U.S. Pat. Nos. 5,534,254, 5,837,242, 6,492,123;U.S. patent application publication Nos. 20040058400 and 20030162709,which are all herein incorporated by reference in their entireties.

The present invention contemplates the use of antibodies recombinantlyfused or chemically conjugated (including both covalently andnon-covalently conjugations) to a polypeptide. Fused or conjugatedantibodies of the present invention may be used for ease inpurification. For example, the antibodies or fragments thereof for usein present invention can be fused to marker sequences, such as a peptideto facilitate purification. See e.g., PCT publication WO 93/21232; EP439,095; Naramura et al., 1994, Immunol Lett 39:91; U.S. Pat. No.5,474,981; Gillies et al., 1992, Proc Natl Acad Sci USA 89:1428; Fell etal., 1991, J Immunol 146:2446, which are herein incorporated byreference in their entireties.

In certain aspects, the antibodies used in the present invention can beproduced intracellularly, in the periplasmic space, or directly secretedinto the medium. If the antibodies are produced intracellularly, as afirst step, the particulate debris, either host cells or lysedfragments, may be removed, for example, by centrifugation orultrafiltration.

Exemplary methods for the use of host cells and vectors in theproduction of antibody can be found in U.S. Pat. Nos. 4,816,567 and6,331,415 to Cabilly et al., each of which is incorporated by referenceherein in its entirety.

5.5 Therapeutic Applications of the B Cell Subset to Treat Diseases andDisorders Associated with Diminished IL-10 Levels

Diseases or disorders associated with diminished levels of IL-10 andelevated immune/inflammatory responses (particularly inflammatorydiseases and autoimmune diseases) can be treated in accordance with theinvention using different therapeutic modalities designed to supply theregulatory B cell subset to an affected subject (e.g., by adoptivetransfer/transplant); expand the endogenous regulatory B cell subset inan affected subject; and/or enhance production of IL-10 by theregulatory B cell subset (either adoptively transferred cells or theendogenous population) in the affected subject.

In one approach, a cellular composition enriched for the IL-10 producingCD1d^(high)CD5⁺ regulatory B cell subset is administered to a subject inneed thereof in amounts effective to increase IL-10. The cellularcomposition can be obtained from a histocompatibilty matched donor.Alternatively, lymphocytes may be obtained from the subject to betreated, enriched for the CD1d^(high)CD5⁺ regulatory B cell subset andreturned to the patient. In either case the enriched cells can beexposed to an antigen of interest prior to introduction into the subjectto further fine-tune the regulation of the immune response.

Alternatively, an effective amount of a therapeutic agent capable ofstimulating the proliferation of the endogenous regulatory B cell subsetthat produces IL-10, and/or increasing the amounts of IL-10 produced bythe endogenous regulatory B cell subset can be administered to a subjectin need thereof in amounts effective to increase IL-10 levels in saidsubject. These agents may be targets to the CD1d^(high)CD5⁺ regulatory Bcell subset.

5.5.1. Diseases and Disorders Associated with Reduced IL-10 Productionthat can be Treated Using the Regulatory B Cell Subset

Diseases and conditions associated with diminished IL-10 levels can betreated in accordance with this aspect of the invention. Decreasedlevels of IL-10 have been demonstrated in autoimmune and inflammatorydiseases including, but not limited to psoriasis (Asadullah et al.,1998, J. Clin. Investig. 101:783-94, Nickoloff et al., 1994, Clin.Immunol. Immunopathol., 73:63-8, Mussi et al. 1994, J. Biol. Regul.Homeostatic Agents), rheumatoid arthritis (Jenkins et al., 1994,Lymphokine Cytokine Res. 13:47-54; Cush et al., 1995, Arthritis Rheum.38:96-104; Al Janadi et al., 1996, J. Clin. Immunol. 16:198-207),allergic contact dermatitis (Kondo et al., 1994, J. Investig. Dermatol.103:811-14; Schwarz et al., 1994, J. Investig. Dermatol. 103:211-16),inflammatory bowel disease (Kuhn et al., 1993, Cell 75:263-74; Lindsayand Hodgson, 2001, Aliment. Pharmacol. Ther. 15:1709-16) and multiplesclerosis (Barrat et al., 2002, J. Exp. Med. 195:603-16; Cua et al.,2001, J. Immunol. 166:602-8; Massey et al., 2002, Vet. Immunol.Immunopathol. 87:357-72; Link and Xiao, 2001, Immunol. Rev. 184:117-28).

Any type of autoimmune disease can be treated in accordance with thismethod of the invention. Non-limiting examples of autoimmune disordersinclude: alopecia greata, ankylosing spondylitis, antiphospholipidsyndrome, autoimmune Addison's disease, autoimmune diseases of theadrenal gland, autoimmune hemolytic anemia, autoimmune hepatitis,autoimmune oophoritis and orchitis, autoimmune thrombocytopenia,Behcet's disease, bullous pemphigoid, cardiomyopathy, celiacsprue-dermatitis, chronic fatigue immune dysfunction syndrome (CFIDS),chronic inflammatory demyelinating polyneuropathy, Churg-Strausssyndrome, cicatrical pemphigoid, CREST syndrome, cold agglutinindisease, Crohn's disease, discoid lupus, essential mixedcryoglobulinemia, fibromyalgia-fibromyositis, glomerulonephritis,Graves' disease, Guillain-Barre, Hashimoto's thyroiditis, idiopathicpulmonary fibrosis, idiopathic thrombocytopenia purpura (ITP), IgAneuropathy, juvenile arthritis, lichen planus, lupus erthematosus,Ménière's disease, mixed connective tissue disease, multiple sclerosis,type 1 or immune-mediated diabetes mellitus, myasthenia gravis,pemphigus vulgaris, pernicious anemia, polyarteritis nodosa,polychrondritis, polyglandular syndromes, polymyalgia rheumatica,polymyositis and dermatomyositis, primary agammaglobulinemia, primarybiliary cirrhosis, psoriasis, psoriatic arthritis, Raynaud's phenomenon,Reiter's syndrome, Rheumatoid arthritis, sarcoidosis, scleroderma,Sjögren's syndrome, stiff-man syndrome, systemic lupus erythematosus,lupus erythematosus, takayasu arteritis, temporal arteritis/giant cellarteritis, ulcerative colitis, uveitis, vasculitides such as dermatitisherpetiformis vasculitis, vitiligo, and Wegener's granulomatosis.Examples of inflammatory disorders include, but are not limited to,asthma, encephilitis, inflammatory bowel disease, chronic obstructivepulmonary disease (COPD), allergic disorders, septic shock, pulmonaryfibrosis, undifferentiated spondyloarthropathy, undifferentiatedarthropathy, arthritis, inflammatory osteolysis, and chronicinflammation resulting from chronic viral or bacteria infections. Asdescribed herein, some autoimmune disorders are associated with aninflammatory condition. Thus, there is overlap between what isconsidered an autoimmune disorder and an inflammatory disorder.Therefore, some autoimmune disorders may also be characterized asinflammatory disorders.

In an aspect of this embodiment, the methods of the invention can beused to treat inflammatory diseases associated with diminished IL-10levels, but not autoimmune diseases.

In another aspect of this embodiMent, the methods of the invention canbe used to treat autoimmune diseases associated with diminished IL-10levels, but not inflammatory diseases.

In yet another aspect of this embodiment, the methods of the inventioncan be used to treat autoimmune diseases associated with diminishedIL-10 levels, wherein the autoimmune disease to be treated is notsystemic lupus erythematosus.

Any type of inflammatory disease can be treated in accordance with thismethod of the invention. Non-limiting examples of inflammatory diseasesinclude, but are not limited to, asthma, encephilitis, inflammatorybowel disease, chronic obstructive pulmonary disease (COPD), allergicdisorders, septic shock, pulmonary fibrosis, undifferentiatedspondyloarthropathy, undifferentiated arthropathy, arthritis,inflammatory osteolysis, and chronic inflammation resulting from chronicviral or bacteria infections.

In still another aspect of this embodiment, the methods of the inventionencompass therapies that are aimed at treating diseases associated witha helper T (Th) 1-mediated inflammatory response but not diseasesassociated with a Th2-mediated inflammatory response.

In an alternative aspect of this embodiment, the methods of theinvention encompass therapies that are aimed at treating diseasesassociated with a Th2-mediated inflammatory response but not diseasesassociated with a Th1-mediated inflammatory response.

IL-10 is capable of inhibiting ischemia/reperfusion injury (Deng et al.,2001, Kidney Int. 60:2118-28), graft-versus-disease, andtransplant-related mortality (Baker et al., 1999, Bone Marrow Transplant23:1123-9; Holler et al., 2000, Bone Marrow Transplant 25:237-41). Assuch, one embodiment of the present invention involves treatingtransplant-associated diseases/conditions by increasing the level ofIL-10 in a patient in need thereof.

In another embodiment, the levels of endogenous IL-10 are increased in asubject receiving an organ transplant by administration of a regulatoryB cell subset. In one aspect of this embodiment, the regulatory B cellpopulation is isolated from the patient themselves, i.e., the subject isthe donor. In another aspect of this embodiment, the regulatory B cellpopulation is isolated from a donor that is not the subject. The donorof the regulatory B cells may be the same as the organ donor. In anotherembodiment, the regulatory B cell population is pooled from severaldonors.

5.5.2. Therapeutic Modalities

In one embodiment, a subject suffering from an autoimmune disease or aninflammatory disease associated with diminished levels of IL-10 isadministered a population of regulatory B cells. In one aspect of thisembodiment, the regulatory B cell population is isolated from thepatient themselves, i.e., the subject is the donor. In another aspect ofthis embodiment, the regulatory B cell population is isolated from adonor that is not the subject. In an aspect of this embodiment, theregulatory B cell population is pooled from several donors. According tothis embodiment, administration of a regulatory B cell population to asubject in need thereof results in an increased level of IL-10production in the patient sufficient to control, reduce, or eliminatesymptoms of the disease being treated.

In one aspect of this embodiment, the therapeutic agent is an antibody,in particular, an anti-CD40 antibody. In other aspects, the therapeuticagent is a small molecule, a polypeptide, DNA, or RNA that interactswith the B cell CD40 receptor.

In another embodiment, a subject suffering from an inflammatory orautoimmune disease associated with diminished levels of IL-10 is treatedby administration of a therapeutic agent capable of causing an increasein IL-10 production by the regulatory B cells in the patient. In aspecific aspect of this embodiment, the therapeutic agent targets the Bcell CD40 receptor. In another aspect of this embodiment, thetherapeutic agent is an anti-CD40 antibody, a small molecule, apolypeptide, DNA, or RNA that is capable of binding, targeting, and ormodulating CD40 so as to result in increase in IL-10 production by theregulatory B cells in the subject.

An antibody according to these embodiments can be any type of antibodyor fragment thereof, as described above. According to this embodimentadministration of an anti-CD40 antibody or fragment thereof to a subjectwith an autoimmune disease or an inflammatory disease associated withdiminished levels of IL-10 results in an upregulation of IL-10production by the endogenous regulatory B cell population in thesubject.

In still another embodiment, a patient receiving a transplant isadministered a therapeutic agent capable of increasing endogenous IL-10production by the regulatory B cell subset of that patient to increasethe patient's tolerance to the transplant. In yet another embodiment, apatient receiving a transplant is administered a regulatory B cellsubset to increase the patient's tolerance to the transplant.

The subject is preferably a mammal such as non-primate (e.g., cows,pigs, horses, cats, dogs, rats, etc.) and a primate (e.g., monkey, suchas a cynomolgous monkey and a human). In a preferred embodiment, thesubject is a human.

5.5.2.1. Regulatory B Cells as Therapeutic Agents

In one embodiment, adoptive transfer of regulatory B cells can beeffective to suppress a wide variety of diseases, including, but notlimited to any of those described above, i.e., autoimmune diseases,inflammatory diseases, or any other disease which may be treated byintroduction of a regulatory B cell population into a subject. Adoptivetransfer of regulatory B cells can further be employed to minimize theimmune/inflammatory response associated with transplant of cells and/ortissues.

In an exemplary adoptive cell transfer protocol, a mixed population of Bcells is initially extracted from a target donor. The regulatory B cellsisolated from the donor may be isolated from any location in the donorin which they reside including, but not limited to, the blood, spleen,lymph nodes, and/or bone marrow of the donor. Depending on theapplication, the B cells may be extracted from a healthy donor; a donorsuffering from a disease that is in a period of remission or duringactive disease; or from the organs, blood, or tissues of a donor thathas died. In the case of the latter, the donor is an organ donor. In yetanother embodiment, the regulatory B cells can be obtained from thesubject, expanded or activated and returned to the subject.

Harvested lymphocytes may be separated by flow cytometry or other cellseparation techniques based on regulatory B cell markers such asdescribed herein, and then transfused to a recipient. Alternatively, thecells may be stored for future use. In one aspect of this embodiment,the donor and the recipient are the same subject. In another aspect ofthis embodiment, the donor is a subject other than the recipient. In afurther aspect of this embodiment, the “donor” comprises multiple donorsother than the recipient, wherein the regulatory B cells from saidmultiple donors are pooled.

In another embodiment, the regulatory B cell population obtained from adonor can be expanded, enriched, or made to produce elevated levels ofIL-10, as described in sections 5.1 and 5.2, supra, prior to beingadministered to a recipient.

In the adoptive transfer techniques contemplated herein, wherein thedonor is a subject other than the recipient, the recipient and the donorare histocompatible. Histocompatibility is the property of having thesame, or mostly the same, alleles of a set of genes called the majorhistocompatibility complex (MHC). These genes are expressed in mosttissues as antigens, to which the immune system makes antibodies. Whentransplanted cells and/or tissues are rejected by a recipient, the bulkof the immune system response is to the MHC proteins. MHC proteins areinvolved in the presentation of foreign antigens to T-cells, andreceptors on the surface of the T-cell are uniquely suited torecognition of proteins of this type. MHC are highly variable betweenindividuals, and therefore the T-cells from the host recognize theforeign MHC with a very high frequency leading to powerful immuneresponses that cause rejection of transplanted tissue. As such, thechance of rejection of the regulatory B cell population by the recipientis minimized.

The amount of regulatory B cells which will be effective in thetreatment and/or suppression of a disease or disorder which may betreated by introduction of a regulatory B cell population into a subjectcan be determined by standard clinical techniques. The dosage willdepend on the type of disease to be treated, the severity and course ofthe disease, the purpose of introducing the regulatory B cellpopulation, previous therapy the recipient has undertaken, therecipient's clinical history, and the discretion of the attendingphysician. The regulatory B cell population can be administered intreatment regimes consistent with the disease, e.g., a single or a fewdoses over one to several days to ameliorate a disease state or periodicdoses over an extended time to inhibit disease progression and preventdisease recurrence. The precise dose to be employed in the formulationwill also depend on the route of administration, and the seriousness ofthe disease or disorder, and should be decided according to the judgmentof the practitioner and each patient's circumstances. Effective dosesmay be extrapolated from dose-response curves derived from in vitro oranimal model test systems. Exemplary, non-limiting doses that could beused in the treatment of human subjects range from at least 3.8×10⁴, atleast 3.8×10⁵, at least 3.8×10⁶, at least 3.8×10⁷, at least 3.8×10⁸, atleast 3.8×10⁹, or at least 3.8×10¹⁰ regulatory B cells/m². In a certainembodiment, the dose used in the treatment of human subjects ranges fromabout 3.8×10⁹ to about 3.8×10¹⁰ regulatory B cells/m².

In another aspect of this embodiment, the regulatory B cells obtainedfrom the donor can be introduced into a recipient at a desired location,so as to specifically target the therapeutic effects of the regulatory Bcell population, i.e., IL-10 production. Such techniques can beaccomplished using implantable immune modulation devices, e.g., virtuallymph nodes, such as those described in U.S. patent applicationpublication No. 2003/0118630; WO1999/044583; and U.S. Pat. No.6,645,500, which are incorporated by reference herein in theirentireties. According to this embodiment, an IL-10 producing regulatoryB cell population can be isolated from a donor as described above, addedto an implantable immune modulation device, and said device then can beimplanted into a recipient at a location where the therapeutic effectsof the regulatory B cell population, i.e., IL-10 production, are needed.

5.5.2.2. Antigen-Specific Regulatory B Cells

In another embodiment, the regulatory B cell population can be maderesponsive to a certain antigen involved in a specific disease. In anaspect of this embodiment, the regulatory B cell population, whensensitized with a certain antigen, will produce therapeutic amounts ofIL-10 upon subsequent encounters with the antigen. In an aspect of thisembodiment, such an antigen-specific regulatory B cell population may beused in an adoptive transfer technique, wherein a subject is or haspreviously been immunized with a certain antigen and theantigen-sensitized regulatory B cells from said subject are isolated andtransplanted to the same or another subject. In still another aspect ofthis embodiment, a regulatory B cell population from a subject can beisolated and subsequently can be sensitized with a disease-specificantigen ex vivo or in vitro. The sensitized regulatory B cell populationcan then be transplanted into the original or another subject by anymethod known in the art. In still another aspect of this embodiment, theantigen-specific regulatory B cell population can be added to animplantable immune modulation device, as described above. According tothis embodiment, the implanted regulatory B cell population will producestrategically localized IL-10 when encountering antigen in the host. Ina further aspect, the regulatory B cell population and adisease-specific antigen can both be placed in an implantable immunemodulation device, and said device then can be transplanted into arecipient at a location where the therapeutic effects of the regulatoryB cell population, i.e., IL-10 production, are needed, thus resulting inan amplified response to the disease in vivo.

In another aspect, a certain disease-specific antigen can beadministered in conjunction with a CD40 agonist. In a certain aspect ofthis embodiment, the therapeutic agent is an antibody, in particular, ananti-CD40 antibody. In other aspects, the therapeutic agent is a smallmolecule, a polypeptide, DNA, or RNA that interacts with the B cell CD40receptor.

Any antigen from any disease, disorder, or condition may be used inaccordance with the methods of the invention. Exemplary antigens includebut are not limited to bacterial, viral, parasitic, allergens,autoantigens and tumor-associated antigens. If a DNA based vaccine isused the antigen will typically be encoded by a sequence of theadministered DNA construct. Alternatively, if the antigen isadministered as a conjugate the antigen will typically be a proteincomprised in the administered conjugate. Particularly, the antigen caninclude protein antigens, peptides, whole inactivated organisms, and thelike.

Specific examples of antigens that can be used in the invention includeantigens from hepatitis A, B, C or D, influenza virus, Listeria,Clostridium botulinum, tuberculosis, tularemia, Variola major(smallpox), viral hemorrhagic fevers, Yersinia pestis (plague), HIV,herpes, pappilloma virus, and other antigens associated with infectiousagents. Other antigens include antigens associated with autoimmuneconditions, inflammatory conditions, allergy, and asthma. Non-limitingexamples of autoimmune diseases and inflammatory diseases are provided,supra.

In an aspect of this embodiment, a regulatory B cell populationsensitized with a disease-specific antigen can be administered alone orin conjunction with a CD40 agonist, in particular, an anti-CD40antibody, for use as a therapeutic or prophylactic vaccine forconferring immunity against such disease conditions.

In another embodiment, a regulatory B cell subset may be sensitized withantigen from a prospective transplant donor, so as to increase thelevels of IL-10 production by the regulatory B cells in a transplantrecipient. In an aspect of this embodiment, the increased IL-10production by the regulatory B cell subset in the transplant recipientresults in a decreased immune/inflammatory response to the transplant inthe transplant recipient. The role of regulatory B cells in transplantsis described in section 5.5.2.3, infra.

5.5.2.3. Regulatory B Cells in Organ Transplant Patients

In another embodiment, the levels of endogenous IL-10 are increased in asubject receiving an organ transplant by administration of a regulatoryB cell subset. In one aspect of this embodiment, the regulatory B cellpopulation is isolated from the patient themselves, i.e., the subject isthe donor. In another aspect of this embodiment, the regulatory B cellpopulation is isolated from a donor that is not the subject. In anaspect of this embodiment, the regulatory B cell population is pooledfrom several donors. In another aspect of this embodiment, theregulatory B cell subset is isolated from a subject that has died,wherein said subject is an organ donor. In embodiments wherein theregulatory B cells are from a donor that is not the subject, the subjectand the donor are histocompatible.

In one aspect of this embodiment, the regulatory B cell subset isadministered prior to the transplant. According to this aspect, thetherapeutic agent can be administered at least 1 hour, at least 12hours, at least 1 day, at least 2 days, at least 3 days, at least 4days, at least 5 days, at least 6 days, at least 1 week, at least 2weeks, at least 3 weeks, at least 4 weeks, or at least 1 month prior tothe transplant. Administration of the therapeutic agent can be by anymethod known to those of skill in the art.

In another aspect of this embodiment, the regulatory B cell subset isadministered at the same time as the transplant.

In still another aspect of this embodiment, the regulatory B cell subsetis administered following the transplant.

In a certain aspect, the regulatory B cell subset is administeredbefore, during, and after the transplant. According to this aspect, whenthe regulatory B cell subset is administered after the transplant, itmay be administered for at least 12 hours, at least 1 day, at least 2days, at least 3 days, at least 4 days, at least 5 days, at least 6days, at least 1 week, at least 2 weeks, at least 3 weeks, at least 4weeks, least 1 month, or at least 1 year following the transplant or forthe duration of the patient's life.

As described in section 5.5.2.2, supra, in one embodiment, a regulatoryB cell subset administered to a patient that is receiving a transplantcan be sensitized with antigens specific to the transplanted material.According to this embodiment, the transplant recipient will have adecreased immune/inflammatory response to the transplanted material and,as such, the likelihood of rejection of the transplanted material isminimized.

In another embodiment, the levels of endogenous IL-10 are increased in asubject receiving an organ transplant by administration of a therapeuticagent capable of causing an increase in IL-10 production by theregulatory B cells in the patient. The therapeutic agent can beadministered in vivo or ex vivo; i.e., the regulatory B cell populationcan be isolated/enriched from the patient, contacted with thetherapeutic agent ex vivo, and the “activated” population returned tothe patient. In a specific aspect of this embodiment, the therapeuticagent targets the B cell CD40 receptor. In another aspect of thisembodiment, the therapeutic agent is an anti-CD40 antibody, a smallmolecule, a polypeptide, DNA, or RNA that is capable of binding,targeting, and or modulating CD40 so as to result in increase in IL-10production by the regulatory B cells in the subject.

In one aspect of this embodiment, the therapeutic agent capable ofcausing an increase in IL-10 production by the regulatory B cells in thepatient is administered prior to the transplant. According to thisaspect, the therapeutic agent can be administered at least 1 hour, atleast 12 hours, at least 1 day, at least 2 days, at least 3 days, atleast 4 days, at least 5 days, at least 6 days, at least 1 week, atleast 2 weeks, at least 3 weeks, at least 4 weeks, or at least 1 monthprior to the transplant. Administration of the therapeutic agent can beby any method known to those of skill in the art.

In another aspect of this embodiment, the therapeutic agent capable ofcausing an increase in IL-10 production by the regulatory B cells in thepatient is administered at the same time as the transplant.

In still another aspect of this embodiment, the therapeutic agentcapable of causing an increase in IL-10 production by the regulatory Bcells in the patient is administered following the transplant.

In a certain aspect, the therapeutic agent capable of causing anincrease in IL-10 production by the regulatory B cells in the patient isadministered before, during, and after the transplant. According to thisaspect, when the therapeutic agent capable of causing an increase inIL-10 production by the regulatory B cells in the patient isadministered after the transplant, it may be administered for at least12 hours, at least 1 day, at least 2 days, at least 3 days, at least 4days, at least 5 days, at least 6 days, at least 1 week, at least 2weeks, at least 3 weeks, at least 4 weeks, least 1 month, or at least 1year following the transplant or for the duration of the patient's life.

According to these embodiments, administration of a therapeutic agentcapable of causing an increase in IL-10 production by the regulatory Bcells in the patient or administration of a regulatory B cell subsetresults in a decreased immune response in the patient receiving thetransplant, wherein the decreased immune response results in anincreased likelihood that the transplant will be accepted, an increasedtolerance to the transplant, an increased duration of time in which thetransplant is accepted, and/or an increased lifespan in the transplantrecipient.

Any type of transplant can be performed according to these methods.

5.6 Therapeutic Targeting of the B Cell Subset to Treat Diseases andDisorders Associated with Enhanced IL-10 Levels

In another embodiment, the invention provides methods for treatingand/or managing a disease or disorder associated with adecreased/depressed/impaired immune/inflammatory response, particularlycancer, by administrating to a subject in need thereof a therapeuticallyor prophylactically effective amount of a therapeutic agent capable ofablating the population of regulatory B cells that produce IL-10 and/orthe amounts of IL-10 being produced by the regulatory B cell subset. Inanother embodiment, the invention provides methods for the treatment ofcancer by administrating to a subject in need thereof a therapeuticallyor prophylactically effective amount of a therapeutic agent capable ofablating the population of regulatory B cells that produce IL-10 and/orthe amounts of IL-10 being produced by the regulatory B cell subset.

In an aspect of this embodiment, the therapeutic agent is an antibodythat mediates CDC or ADCC and kills target cells, or an immunoconjugatethat alters the function of or kills target cells is used. Inparticular, an anti-CD22 mAb that kills or inhibits the proliferation ofthe regulatory B cell subset can be used. Alternatively, a bispecificanti-CD1d/CD5 antibody can be used.

In another aspect Of this embodiment, the therapeutic agent is anantibody that does not utilize CDC or ADCC to kill the target cells. Inanother aspect, the antibody does not kill the target cells byapoptosis.

In another aspect of this embodiment, the therapeutic agent is anantibody that does not utilize CDC, ADCC, or apoptosis as the primarymechanism for killing target cells, i.e., the majority of target cellsare killed by a mechanism that is CDC-, ADCC-, andapoptosis-independent.

In another aspect of this embodiment, the therapeutic agent is a smallmolecule, a polypeptide, DNA, or RNA that interacts with the B cell CD22receptor or with the CD1d or CD5 receptors.

The subject is preferably a mammal such as non-primate (e.g., cows,pigs, horses, cats, dogs, rats, etc.) and a primate (e.g., monkey, suchas a cynomolgous monkey and a human). In a preferred embodiment, thesubject is a human.

5.6.1 Diseases and Disorders Associated with Increased IL-10 Production

IL-10 has been shown to promote tumor growth and overexpression of IL-10has been demonstrated in certain cancers (Matsuda et al., 1994, J. Exp.Med. 180:2371-6; Salazar-Onfray et al., 1997, J. Immunol. 159:3195-3202;Hagenbaugh et al. 1997, J. Exp. Med. 185:2101-110; Kruger-Kraskagakes etal. 1994, Br. J. Cancer 70:1182-5, Dummer et al., 1996, Int. J. Cancer66:607-10; Kim et al., 1995, J. Immunol. 155:2240-47; Blay et al., 1993,Blood 82:2169-74; Asadullah et al., 2000, Exp. Dermatol. 9:71-6). Assuch, one embodiment of the present invention involves treating cancerby decreasing the level of IL-10 in a patient in need thereof byablation of the IL-10 producing regulatory B cell subset and/or reducingthe amount of IL-10 produced by the IL-10 producing regulatory B cellsubset.

Any type of cancer can be treated in accordance with this method of theinvention. Non-limiting examples of cancers include: leukemias, such asbut not limited to, acute leukemia, acute lymphocytic leukemia, acutemyelocytic leukemias, such as, myeloblastic, promyelocytic,myelomonocytic, monocytic, and erythroleukemia leukemias andmyelodysplastic syndrome; chronic leukemias, such as but not limited to,chronic myelocytic (granulocytic) leukemia, chronic lymphocyticleukemia, hairy cell leukemia; polycythemia vera; lymphomas such as butnot limited to Hodgkin's disease, non-Hodgkin's disease; multiplemyelomas such as but not limited to smoldering multiple myeloma,nonsecretory myeloma, osteosclerotic myeloma, plasma cell leukemia,solitary plasmacytoma and extramedullary plasmacytoma; Waldenstrom'smacroglobulinemia; monoclonal gammopathy of undetermined significance;benign monoclonal gammopathy; heavy chain disease; bone and connectivetissue sarcomas such as but not limited to bone sarcoma, osteosarcoma,chondrosarcoma, Ewing's sarcoma, malignant giant cell tumor,fibrosarcoma of bone, chordoma, periosteal sarcoma, soft-tissuesarcomas, angiosarcoma (hemangiosarcoma), fibrosarcoma, Kaposi'ssarcoma, leiomyosarcoma, liposarcoma, lymphangiosarcoma, neurilemmoma,rhabdomyosarcoma, synovial sarcoma; brain tumors such as but not limitedto, glioma, astrocytoma, brain stem glioma, ependymoma,oligodendroglioma, nonglial tumor, acoustic neurinoma,craniopharyngioma, medulloblastoma, meningioma, pineocytoma,pineoblastoma, primary brain lymphoma; breast cancer including but notlimited to ductal carcinoma, adenocarcinoma, lobular (small cell)carcinoma, intraductal carcinoma, medullary breast cancer, mucinousbreast cancer, tubular breast cancer, papillary breast cancer, Paget'sdisease, and inflammatory breast cancer; adrenal cancer such as but notlimited to pheochromocytom and adrenocortical carcinoma; thyroid cancersuch as but not limited to papillary or follicular thyroid cancer,medullary thyroid cancer and anaplastic thyroid cancer; pancreaticcancer such as but not limited to, insulinoma, gastrinoma, glucagonoma,vipoma, somatostatin-secreting tumor, and carcinoid or islet cell tumor;pituitary cancers such as but limited to Cushing's disease,prolactin-secreting tumor, acromegaly, and diabetes insipius; eyecancers such as but not limited to ocular melanoma such as irismelanoma, choroidal melanoma, and cilliary body melanoma, andretinoblastoma; vaginal cancers such as squamous cell carcinoma,adenocarcinoma, and melanoma; vulvar cancer such as squamous cellcarcinoma, melanoma, adenocarcinoma, basal cell carcinoma, sarcoma, andPaget's disease; cervical cancers such as but not limited to, squamouscell carcinoma, and adenocarcinoma; uterine cancers such as but notlimited to endometrial carcinoma and uterine sarcoma; ovarian cancerssuch as but not limited to, ovarian epithelial carcinoma, borderlinetumor, germ cell tumor, and stromal tumor; esophageal cancers such asbut not limited to, squamous cancer, adenocarcinoma, adenoid cysticcarcinoma, mucoepidermoid carcinoma, adenosquamous carcinoma, sarcoma,melanoma, plasmacytoma, verrucous carcinoma, and oat cell (small cell)carcinoma; stomach cancers such as but not limited to, adenocarcinoma,fungating (polypoid), ulcerating, superficial spreading, diffuselyspreading, malignant lymphoma, liposarcoma, fibrosarcoma, andcarcinosarcoma; colon cancers; rectal cancers; liver cancers such as butnot limited to hepatocellular carcinoma and hepatoblastoma; gallbladdercancers such as adenocarcinoma; cholangiocarcinomas such as but notlimited to papillary, nodular, and diffuse; lung cancers such asnon-small cell lung cancer, squamous cell carcinoma (epidermoidcarcinoma), adenocarcinoma, large-cell carcinoma and small-cell lungcancer; testicular cancers such as but not limited to germinal tumor,seminoma, anaplastic, classic (typical), spermatocytic, nonseminoma,embryonal carcinoma, teratoma carcinoma, choriocarcinoma (yolk-sactumor), prostate cancers such as but not limited to, prostaticintraepithelial neoplasia, adenocarcinoma, leiomyosarcoma, andrhabdomyosarcoma; penal cancers; oral cancers such as but not limited tosquamous cell carcinoma; basal cancers; salivary gland cancers such asbut not limited to adenocarcinoma, mucoepidermoid carcinoma, andadenoidcystic carcinoma; pharynx cancers such as but not limited tosquamous cell cancer, and verrucous; skin cancers such as but notlimited to, basal cell carcinoma, squamous cell carcinoma and melanoma,superficial spreading melanoma, nodular melanoma, lentigo malignantmelanoma, acral lentiginous melanoma; kidney cancers such as but notlimited to renal cell carcinoma, adenocarcinoma, hypernephroma,fibrosarcoma, transitional cell cancer (renal pelvis and/or uterer);Wilms' tumor; bladder cancers such as but not limited to transitionalcell carcinoma, squamous cell cancer, adenocarcinoma, carcinosarcoma. Inaddition, cancers include myxosarcoma, osteogenic sarcoma,endotheliosarcoma, lymphangioendotheliosarcoma, mesothelioma, synovioma,hemangioblastoma, epithelial carcinoma, cystadenocarcinoma, bronchogeniccarcinoma, sweat gland carcinoma, sebaceous gland carcinoma, papillarycarcinoma and papillary adenocarcinomas (for a review of such disorders,see Fishman et al, 1985, Medicine, 2d Ed., J.B. Lippincott Co.,Philadelphia and Murphy, 1997, Informed Decisions: The Complete Book ofCancer Diagnosis, Treatment, and Recovery, Viking Penguin, Penguin BooksU.S.A., Inc., United States of America, incorporated by reference hereinin its entirety).

Increased levels of IL-10 have been demonstrated in certain autoimmuneand inflammatory diseases including, but not limited to systemic lupuserythematosus (Park et al., 1998, Clin. Exp. Rheumatol. 16:283-88;Llorente et al., 1995, J. Exp. Med. 181:839-44), systemic sclerosis(Hasegawa et al., 1997, J. Rheumatol. 24:328-32), Bullous Pemphigoid(Schmidt et al., 1996, Arch. Dermatol. Res. 228:353-7; Giacalone et al.,1998, Exp. Dermatol. 7:157-61), and atopic dermatitis (Ohmen et al.,1995, J. Immunol. 154:1956-63; Asadullah et al., 1996, J. Investig.Dermatol. 197:833-7). As such, one embodiment of the present inventioninvolves treating an autoimmune or inflammatory by decreasing the levelof IL-10 in a patient in need thereof by ablation of the IL-10 producingregulatory B cell subset and/or reducing the amount of IL-10 produced bythe IL-10 producing regulatory B cell subset.

Any type of autoimmune disease that is accompanied by increased IL-10production can be treated in accordance with this method of theinvention. A non-limiting list of autoimmune disorders is providedabove.

Any type of inflammatory disease that is accompanied by increased IL-10production can be treated in accordance with this method of theinvention. A non-limiting list of inflammatory diseases is providedabove.

In an aspect of this embodiment, the methods of the invention can beused to treat inflammatory diseases associated with diminished IL-10levels, but not autoimmune diseases.

In another aspect of this embodiment, the methods of the invention canbe used to treat autoimmune diseases associated with diminished IL-10levels, but not inflammatory diseases.

In yet another aspect of this embodiment, the methods of the inventioncan be used to treat autoimmune diseases associated with diminishedIL-10 levels, wherein the autoimmune disease to be treated is notsystemic lupus erythematosus.

In still another aspect of this embodiment, the methods of the inventionencompass therapies that are aimed at treating diseases associated witha helper T (Th) 1-mediated inflammatory response but not diseasesassociated with a Th2-mediated inflammatory response.

In an alternative aspect of this embodiment, the methods of theinvention encompass therapies that are aimed at treating diseasesassociated with a Th2-mediated inflammatory response but not diseasesassociated with a Th1-mediated inflammatory response.

5.6.2 Therapies

In one embodiment, a subject suffering from cancer who has elevatedlevels of IL-10 is treated by administration of a therapeutic agentcapable of ablating the population of regulatory B cells in the patientand/or reducing the amount of IL-10 production produced by theregulatory B cell population. In a specific aspect of this embodiment,the therapeutic agent targets the B cell CD22 receptor. In anotheraspect of this embodiment, the therapeutic agent is an anti-CD22antibody, a small molecule, a polypeptide, DNA, or RNA that is capableof binding, targeting, and or modulating CD22 so as to result inablation of the regulatory B cell subset.

In another embodiment, a subject suffering from an immune deficiencydisease associated with elevated levels of IL-10 is treated byadministration of a therapeutic agent capable of ablating the populationof regulatory B cells in the patient and thereby reducing the amount ofIL-10 production produced by the regulatory B cell population. In aspecific aspect of this embodiment, the therapeutic agent targets the Bcell CD22 receptor. In another aspect of this embodiment, thetherapeutic agent is an anti-CD22 antibody, a small molecule, apolypeptide, DNA, or RNA that is capable of binding, targeting, and ormodulating CD22 so as to result in ablation of the regulatory B cellsubset.

In an alternative embodiment, a subject suffering from cancer or animmune deficiency disease associated with elevated levels of IL-10 istreated by administration of a bispecific anti-CD1d/CD5 antibody capableof ablating the population of regulatory B cells in the patient andthereby reducing the amount of IL-10 produced.

In order to kill or ablate the regulatory B cell subset, targetingantibodies (e.g., anti-CD22 or bispecific anti-CD1d/CD5) of an isotypethat mediate ADCC (antibody-dependent and mediated toxicity) or CDC(complement-dependent cytotoxicity) can be used. Of the various humanimmunoglobulin classes, IgG1, IgG2, IgG3, IgG4 and IgM are known toactivate complement. Human IgG1 and IgG3 are known to mediate ADCC.

Antibodies targeting the CD1d^(high)CD5⁺ regulatory B cell subset can befurther conjugated to a cytotoxic agent, using methods known in the art(see, e.g., DiJoseph et al., 2004, Clin. Cancer Res. 10:8620-9). Thismay be preferred when using antibodies or antibody fragments that do notmediate ADCC or CDC. Non-limiting examples of cytotoxic agents includeantimetabolites (e.g., cytosine arabinoside, aminopterin, methotrexate,6-mercaptopurine, 6-thioguanine, cytarabine, and 5-fluorouracildecarbazine); alkylating agents (e.g., mechlorethamine, thiotepachlorambucil, melphalan, carmustine (BCNU) and lomustine (CCNU),cyclophosphamide, busulfan, dibromomannitol, streptozotocin, mitomycinC, cis-dichlorodiammine-platinum (II) (CDDP), and cisplatin); vincaalkaloid; anthracyclines (e.g., daunorubicin (formerly daunomycin) anddoxorubicin); antibiotics (e.g., dactinomycin (formerly actinomycin),bleomycin, mithramycin, and anthramycin (AMC)); calicheamicin; CC-1065and derivatives thereof; auristatin molecules (e.g., auristatin PHE,bryostatin-1, and dolastatin-10; see Woyke et al., Antimicrob. AgentsChemother 46:3802-8 (2002), Woyke et al., Antimicrob. Agents Chemother.45:3580-4 (2001), Mohammad et al., Anticancer Drugs 12:735-40 (2001),Wall et al., Biochem. Biophys. Res. Commun. 266:76-80 (1999), Mohammad,et al., Int. J. Oncol. 15:367-72 (1999), all of which are incorporatedby reference herein in their entireties); DNA-repair enzyme inhibitors(e.g., etoposide or topotecan); kinase inhibitors (e.g., compoundST1571, imatinib mesylate (Kantarjian et al., Clin. Cancer Res.8(7):2167-76 (2002)); demecolcine; and other cytotoxic agents (e.g.,paclitaxel, cytochalasin B, gramicidin D, ethidium bromide, emetine,mitomycin, etoposide, tenoposide, vincristine, vinblastine, colchicine,doxorubicin, daunorubicin, dihydroxy anthracenedione, mitoxantrone,mithramycin, actinomycin D, 1-dehydrotestosterone, glucorticoids,procaine, tetracaine, lidocaine, propranolol, and puromycin and analogsor homologues thereof and those compounds disclosed in U.S. Pat. Nos.6,245,759, 6,399,633, 6,383,790, 6,335,156, 6,271,242, 6,242,196,6,218,410, 6,218,372, 6,057,300, 6,034,053, 5,985,877, 5,958,769,5,925,376, 5,922,844, 5,911,995, 5,872,223, 5,863,904, 5,840,745,5,728,868, 5,648,239, 5,587,459, all of which are incorporated byreference herein in their entirety); farnesyl transferase inhibitors(e.g., R115777, BMS-214662, and those disclosed by, for example, U.S.Pat. Nos. 6,458,935, 6,451,812, 6,440,974, 6,436,960, 6,432,959,6,420,387, 6,414,145, 6,410,541, 6,410,539, 6,403,581, 6,399,615,6,387,905, 6,372,747, 6,369,034, 6,362,188, 6,342,765, 6,342,487,6,300,501, 6,268,363, 6,265,422, 6,248,756, 6,239,140, 6,232,338,6,228,865, 6,228,856, 6,225,322, 6,218,406, 6,211,193, 6,187,786,6,169,096, 6,159,984, 6,143,766, 6,133,303, 6,127,366, 6,124,465,6,124,295, 6,103,723, 6,093,737, 6,090,948, 6,080,870, 6,077,853,6,071,935, 6,066,738, 6,063,930, 6,054,466, 6,051,582, 6,051,574, and6,040,305, all of which are herein incorporated by reference in theirentirety); topoisomerase inhibitors (e.g., camptothecin, irinotecan,SN-38, topotecan, 9-aminocamptothecin, GG211 (GI147211), DX-8951f,IST-622, rubitecan, pyrazoloacridine, XR5000, saintopin, UCE6, UCE1022,TAN-1518A, TAN 1518B, KT6006, KT6528, ED-110, NB-506, ED-110, NB-506,and rebeccamycin); bulgarein; DNA minor groove binders such as Hoechstdye 33342 and Hoechst dye 33258; nitidine; fagaronine; epiberberine;coralyne; beta-lapachone; BC-4-1; antisense oligonucleotides (e.g.,those disclosed in the U.S. Pat. Nos. 6,277,832, 5,998,596, 5,885,834,5,734,033, and 5,618,709, all of which are herein incorporated byreference in their entirety); adenosine deaminase inhibitors (e.g.,fludarabine phosphate and 2-chlorodeoxyadenosine); and pharmaceuticallyacceptable salts, solvates, clathrates, and prodrugs thereof.

In another embodiment, the antibody that targets the CD1d^(high)CD5⁺regulatory B cell population, the anti-CD22 or bispecific anti-CD1d/CD5antibody can be conjugated to a radioactive metal ion, such as thealpha-emitters ²¹¹astatine, ²¹²bismuth, ²¹³bismuth; the beta-emitters¹³¹iodine, ⁹⁰yttrium, ¹⁷⁷lutetium, ¹⁵³samarium, and ¹⁰⁹palladium; ormacrocyclic chelators useful for conjugating radiometal ions, includingbut not limited to, ¹³¹indium, ¹³¹L, ¹³¹yttrium, ¹³¹holmium,¹³¹samarium, to polypeptides or any of those listed supra. In certainembodiments, the macrocyclic chelator is1,4,7,10-tetraazacyclododecane-N,N′,N″,N′″-tetraacetic acid (DOTA),which can be attached to the antibody via a linker molecule. Such linkermolecules are commonly known in the art and described in Denardo, etal., 1998, Clin Cancer Res 4(10):2483-90; Peterson, et al., 1999,Bioconjug Chem 10(4):553-7; and Zimmerman, et al., 1999, Nucl Med Biol26(8):943-50, each incorporated by reference herein in their entireties.

In still another embodiment, the antibody that targets theCD1d^(high)CD5⁺ regulatory B cell population, the anti-CD22 antibody, orbispecific anti-CD1d/CD5 antibody is conjugated to a proteinaceous agentthat modifies a given biological response and leads to cytotoxicity. Inone embodiment, the antibody is conjugated to a plant-, fungus-, orbacteria-derived toxin. Non-limiting examples of such toxins include Achain toxins, ribosome inactivating proteins, ricin A, deglycosylatedricin A chain, abrin, alpha sarcin, aspergillin, restrictocin,ribonucleases, diphtheria toxin, bacterial endotoxin, saporin toxin,Granzyme B or the lipid A moiety of bacterial endotoxin, cholera toxin,or Pseudomonas exotoxin and derivatives and variants thereof.

In another embodiment, an antagonist capable of engaging CD22 to ablatethe regulatory B cell population is a synthetic CD22 ligand, such asthat described in Collins et al., 2006, J. Immunol. 5:2994-3003,incorporated herein by reference in its entirety. In one aspect of thisembodiment, the synthetic CD22 ligand may be further conjugated to atoxin, such as the saporin toxin.

In an alternative embodiment, a subject suffering from cancer or animmune deficiency disease associated with elevated levels of IL-10 istreated by administration of a compound capable of engaging a marker ormarkers on the regulatory B cell subset can inhibit the production ofIL-10 by the regulatory B cells. Non-limiting examples of such compoundsinclude antibodies and fragments thereof, small molecules, syntheticdrugs, peptides (including cyclic peptides), polypeptides, proteins,nucleic acids, synthetic or natural inorganic molecules, mimetic agents,and synthetic or natural organic molecules. In one embodiment, thecompound engages CD22. In an aspect of this embodiment, the compound isan anti-CD22 antibody. In another aspect of this embodiment, thecompound engages CD5. In an aspect of this embodiment, the compound isan anti-CD5 antibody. In another aspect of this embodiment, the compoundengages CD1d. In an aspect of this embodiment, the compound is ananti-CD1d antibody. In still another aspect of this embodiment, thecompound is a bispecific anti-CD1d/CD5 antibody. In yet another aspectof this embodiment, the compound engages CD19. In an aspect of thisembodiment, the compound is an anti-CD19 antibody.

An antibody according to these embodiments can be any type of antibodyor fragment thereof, as described above. According to this embodiment,administration of an antibody that targets the CD1d^(high)CD5⁺regulatory B cell population or fragment thereof, including an anti-CD22antibody or fragment thereof to a patient with cancer, an autoimmunedisease, or an inflammatory disease associated with increased levels ofIL-10 results in a downregulation of IL-10 production by the regulatoryB cell population in the patient.

In another embodiment, a patient suffering from cancer or an immunedeficiency disease associated with elevated levels of IL-10 is treatedby administration of an antibody that binds to a B cell marker andselectively depletes the regulatory B cell population in the patient.According to this embodiment, the B cell marker can be any antigen thatis presently known or subsequently determined to be expressed byregulatory B cells including, e.g. CD5, CD19, CD20, CD21, CD22, CD24,CD40 and CD72. In one aspect of this embodiment, the antibody that bindsto a B cell marker and selectively depletes the regulatory B cellpopulation in the patient does not cause depletion of the regulatory Bcell population by an antibody-dependent cell-mediated cytotoxicity(ADCC) mechanism, by complement-dependent cytotoxicity (CDC), or byapoptosis. In another aspect, depletion of the regulatory B cellpopulation by the antibody is independent of the antibody's Fc region.In another aspect of this embodiment, the antibody that binds to a Bcell marker and selectively depletes the regulatory B cell populationdepletes splenic Marginal Zone B cells but does not substantiallydeplete splenic Follicular B cells. In a specific aspect, the antibodythat binds to a B cell marker and selectively depletes the regulatory Bcell population is an IgG2b or an IgG3 isotype.

In another embodiment, the antibody for use in treating a patientsuffering from cancer or an immune deficiency disease associated withelevated levels of IL-10 that binds to a B cell marker and selectivelydepletes the regulatory B cell population comprises a human IgG isotypeor Fc region that does not activate complement or lead to ADCC or killcells by inducing apoptosis. Any human isotype or Fc region that doesnot activate complement or lead to ADCC or kill cells by inducingapoptosis can be used in accordance with this embodiment. In one aspect,the isotype is IgG4.

In a specific embodiment, a patient suffering from cancer is treated byadministration of an anti-CD20 antibody that selectively depletes theregulatory B cell population in the patient, wherein the depletion ofthe regulatory B cell population by the anti-CD20 antibody is not causedby ADCC, CDC, or apoptosis. In another aspect, depletion of theregulatory B cell population by the antibody is independent of theantibody's Fc region. In an aspect of this embodiment, the anti-CD20antibody depletes splenic Marginal Zone B cells but does notsubstantially deplete splenic Follicular B cells. In a specific aspect,the anti-CD20 is an IgG2b or an IgG3 isotype. In another aspect, theanti-CD20 antibody comprises a human IgG isotype or Fc region that doesnot activate complement or lead to ADCC or cells by inducing apoptosis.Any human isotype or Fc region that does not activate complement or leadto ADCC or kill cells by inducing apoptosis can be used in accordancewith this embodiment. In one aspect, the isotype is IgG4.

In certain embodiments, the regulatory B cell population is depleted byat least 1%, at least 1% to 5%, at least 1% to 10%, at least 1% to 25%,at least 1% to 50%, at least 55%, at least 60%, at least 65%, at least70%, at least 75%, at least 80%, at least 85%, at least 90%, at least95%, at least 99%, or by 100% as measured by an assay known to one ofskill in the art, e.g., immunofluorescence staining with flow cytometryanalysis, ELISA assay for IL-10 secretion, or ELISpot analysis fordetermining numbers of IL-10-secreting cells.

In certain embodiments, the antibodies described herein are administeredalone. In other embodiments, the antibodies described herein areadministered to patients as a front-line therapy. In other embodiments,the antibodies described herein are administered to patients as asecondary therapy. In certain embodiments, the patient has notpreviously been treated for the cancer or the immune deficiency disease.In other embodiments, the patient is undergoing or has undergonetreatment for the cancer or the immune deficiency disease. In yet otherembodiments, the patient has failed treatment for the cancer or theimmune deficiency disease.

In certain embodiments, the antibodies described herein are administeredin combination with other therapeutic agents. Any therapy that isuseful, has been used, or is currently being used for the prevention,treatment, and/or management of cancer or an immune deficiency diseasecan be used in compositions and methods of the invention. Such therapiesinclude, but are not limited to, peptides, polypeptides, antibodies,conjugates, nucleic acid molecules, small molecules, mimetic agents,synthetic drugs, inorganic molecules, and organic molecules.

Non-limiting examples of cancer therapies include chemotherapy,radiation therapy, hormonal therapy, surgery, small molecule therapy,anti-angiogenic therapy, differentiation therapy, epigenetic therapy,radioimmunotherapy, targeted therapy, and/or biological therapyincluding immunotherapy including, but not limited to acivicin;aclarubicin; acodazole hydrochloride; acronine; adozelesin; aldesleukin;altretamine; ambomycin; ametantrone acetate; aminoglutethimide;amsacrine; anastrozole; anthracyclin; anthramycin; asparaginase;asperlin; azacitidine (Vidaza); azetepa; azotomycin; batimastat;benzodepa; bicalutamide; bisantrene hydrochloride; bisnafide dimesylate;bisphosphonates (e.g., pamidronate (Aredria), sodium clondronate(Bonefos), zoledronic acid (Zometa), alendronate (Fosamax), etidronate,ibandornate, cimadronate, risedromate, and tiludromate); bizelesin;bleomycin sulfate; brequinar sodium; bropirimine; busulfan;cactinomycin; calusterone; caracemide; carbetimer; carboplatin;carmustine; carubicin hydrochloride; carzelesin; cedefingol;chlorambucil; cirolemycin; cisplatin; cladribine; crisnatol mesylate;cyclophosphamide; cytarabine (Ara-C); dacarbazine; dactinomycin;daunorubicin hydrochloride; decitabine (Dacogen); demethylation agents,dexormaplatin; dezaguanine; dezaguanine mesylate; diaziquone; docetaxel;doxorubicin; doxorubicin hydrochloride; droloxifene; droloxifenecitrate; dromostanolone propionate; duazomycin; edatrexate; eflornithinehydrochloride; EphA2 inhibitors; elsamitrucin; enloplatin; enpromate;epipropidine; epirubicin hydrochloride; erbulozole; esorubicinhydrochloride; estramustine; estramustine phosphate sodium; etanidazole;etoposide; etoposide phosphate; etoprine; fadrozole hydrochloride;fazarabine; fenretinide; floxuridine; fludarabine phosphate;fluorouracil; fluorocitabine; fosquidone; fostriecin sodium;gemcitabine; histone deacetylase inhibitors (HDACs) gemcitabinehydrochloride; hydroxyurea; idarubicin hydrochloride; ifosfamide;ilmofosine; imatinib mesylate (Gleevec, Glivec); interleukin II(including recombinant interleukin II, or rIL2), interferon alpha-2a;interferon alpha-2b; interferon alpha-nl; interferon alpha-n3;interferon beta-I a; interferon gamma-I b; iproplatin; irinotecanhydrochloride; lanreotide acetate; lenalidomide (Revlimid); letrozole;leuprolide acetate; liarozole hydrochloride; lometrexol sodium;lomustine; losoxantrone hydrochloride; masoprocol; maytansine;mechlorethamine hydrochloride; anti-CD2 antibodies (e.g., siplizumab(MedImmune Inc.; International Publication No. WO 02/098370, which isincorporated herein by reference in its entirety)); megestrol acetate;melengestrol acetate; melphalan; menogaril; mercaptopurine;methotrexate; methotrexate sodium; metoprine; meturedepa; mitindomide;mitocarcin; mitocromin; mitogillin; mitomalcin; mitomycin; mitosper;mitotane; mitoxantrone hydrochloride; mycophenolic acid; nocodazole;nogalamycin; ormaplatin; oxaliplatin; oxisuran; paclitaxel;pegaspargase; peliomycin; pentamustine; peplomycin sulfate;perfosfamide; pipobroman; piposulfan; piroxantrone hydrochloride;plicamycin; plomestane; porfimer sodium; porfiromycin; prednimustine;procarbazine hydrochloride; puromycin; puromycin hydrochloride;pyrazofurin; riboprine; rogletimide; safingol; safingol hydrochloride;semustine; simtrazene; sparfosate sodium; sparsomycin; spirogermaniumhydrochloride; spiromustine; spiroplatin; streptonigrin; streptozocin;sulofenur; talisomyciri; tecogalan sodium; tegafur; teloxantronehydrochloride; temoporfin; teniposide; teroxirone; testolactone;thiamiprine; thioguanine; thiotepa; tiazofurin; tirapazamine; toremifenecitrate; trestolone acetate; triciribine phosphate; trimetrexate;trimetrexate glucuronate; triptorelin; tubulozole hydrochloride; uracilmustard; uredepa; vapreotide; verteporfin; vinblastine sulfate;vincristine sulfate; vindesine; vindesine sulfate; vinepidine sulfate;vinglycinate sulfate; vinleurosine sulfate; vinorelbine tartrate;vinrosidine sulfate; vinzolidine sulfate; vorozole; zeniplatin;zinostatin; zorubicin hydrochloride; 20-epi-1,25 dihydroxyvitamin D3;5-ethynyluracil; abiraterone; aclarubicin; acylfulvene; adecypenol;adozelesin; aldesleukin; ALL-TK antagonists; altretamine; ambamustine;amidox; amifostine; aminolevulinic acid; amrubicin; amsacrine;anagrelide; anastrozole; andrographolide; angiogenesis inhibitors;antagonist D; antagonist G; antarelix; anti-dorsalizing morphogeneticprotein-1; antiandrogen, prostatic carcinoma; antiestrogen;antineoplaston; antisense oligonucleotides; aphidicolin glycinate;apoptosis gene modulators; apoptosis regulators; apurinic acid;ara-CDP-DL-PTBA; arginine deaminase; asulacrine; atamestane;atrimustine; axinastatin 1; axinastatin 2; axinastatin 3; azasetron;azatoxin; azatyrosine; baccatin III derivatives; balanol; batimastat;BCR/ABL antagonists; benzochlorins; benzoylstaurosporine; beta lactamderivatives; beta-alethine; betaclamycin B; betulinic acid; bFGFinhibitor; bicalutamide; bisantrene; bisaziridinylspermine; bisnafide;bistratene A; bizelesin; breflate; bropirimine; budotitane; buthioninesulfoximine; calcipotriol; calphostin C; camptothecin derivatives;canarypox IL-2; capecitabine; carboxamide-amino-triazole;carboxyamidotriazole; CaRest M3; CARN 700; cartilage derived inhibitor;carzelesin; casein kinase inhibitors (ICOS); castanospermine; cecropinB; cetrorelix; chlorins; chloroquinoxaline sulfonamide; cicaprost;cis-porphyrin; cladribine; clomifene analogues; clotrimazole;collismycin A; collismycin B; combretastatin A4; combretastatinanalogue; conagenin; crambescidin 816; crisnatol; cryptophycin 8;cryptophycin A derivatives; curacin A; cyclopentanthraquinones;cycloplatam; cypemycin; cytarabine ocfosfate; cytolytic factor;cytostatin; dacliximab; decitabine; dehydrodidemnin B; deslorelin;dexamethasone; dexifosfamide; dexrazoxane; dexverapamil; diaziquone;didemnin B; didox; diethylnorspermine; dihydro-5-azacytidine;dihydrotaxol, dioxamycin; diphenyl spiromustine; docetaxel; docosanol;dolasetron; doxifluridine; droloxifene; dronabinol; duocarmycin SA;ebselen; ecomustine; edelfosine; edrecolomab; eflornithine; elemene;emitefur; epirubicin; epristeride; estramustine analogue; estrogenagonists; estrogen antagonists; etanidazole; etoposide phosphate;exemestane; fadrozole; fazarabine; fenretinide; filgrastim; finasteride;flavopiridol; flezelastine; fluasterone; fludarabine; fluorodaunorunicinhydrochloride; forfenimex; formestane; fostriecin; fotemustine;gadolinium texaphyrin; gallium nitrate; galocitabine; ganirelix;gelatinase inhibitors; gemcitabine; glutathione inhibitors; HMG CoAreductase inhibitors (e.g., atorvastatin, cerivastatin, fluvastatin,lescol, lupitor, lovastatin, rosuvastatin, and simvastatin); hepsulfam;heregulin; hexamethylene bisacetamide; hypericin; ibandronic acid;idarubicin; idoxifene; idramantone; ilmofosine; ilomastat;imidazoacridones; imiquimod; immunostimulant peptides; insulin-likegrowth factor-1 receptor inhibitor; interferon agonists; interferons;interleukins; iobenguane; iododoxorubicin; ipomeanol, 4-iroplact;irsogladine; isobengazole; isohomohalicondrin B; itasetron;jasplakinolide; kahalalide F; lamellarin-N triacetate; lanreotide;leinamycin; lenograstim; lentinan sulfate; leptolstatin; letrozole;leukemia inhibiting factor; leukocyte alpha interferon;leuprolide+estrogen+progesterone; leuprorelin; levamisole; LFA-3TIP(Biogen, Cambridge, Mass.; International Publication No. WO 93/0686 andU.S. Pat. No. 6,162,432); liarozole; linear polyamine analogue;lipophilic disaccharide peptide; lipophilic platinum compounds;lissoclinamide 7; lobaplatin; lombricine; lometrexol; lonidamine;losoxantrone; lovastatin; loxoribine; lurtotecan; lutetium texaphyrin;lysofylline; lytic peptides; maitansine; mannostatin A; marimastat;masoprocol; maspin; matrilysin inhibitors; matrix metalloproteinaseinhibitors; menogaril; merbarone; meterelin; methioninase;metoclopramide; MIF inhibitor; mifepristone; miltefosine; mirimostim;mismatched double stranded RNA; mitoguazone; mitolactol; mitomycinanalogues; mitonafide; mitotoxin fibroblast growth factor-saporin;mitoxantrone; mofarotene; molgramostim; monoclonal antibody, humanchorionic gonadotrophin; monophosphoryl lipid A+myobacterium cell wallsk; mopidamol; multiple drug resistance gene inhibitor; multiple tumorsuppressor 1-based therapy; mustard anticancer agent; mycaperoxide B;mycobacterial cell wall extract; myriaporone; N-acetyldinaline;N-substituted benzamides; nafarelin; nagrestip; naloxone+pentazocine;napavin; naphterpin; nartograstim; nedaplatin; nemorubicin; neridronicacid; neutral endopeptidase; nilutamide; nisamycin; nitric oxidemodulators; nitroxide antioxidant; nitrullyii; O6-benzylguanine;octreotide; okicenone; oligonucleotides; onapristone; ondansetron;ondansetron; oracin; oral cytokine inducer; ormaplatin; osaterone;oxaliplatin; oxaunomycin; paclitaxel; paclitaxel analogues; paclitaxelderivatives; palauamine; palmitoylrhizoxin; pamidronic acid;panaxytriol; panomifene; parabactin; pazelliptine; pegaspargase;peldesine; pentosan polysulfate sodium; pentostatin; pentrozole;perflubron; perfosfamide; perillyl alcohol; phenazinomycin;phenylacetate; phosphatase inhibitors; picibanil; pilocarpinehydrochloride; pirarubicin; piritrexim; placetin A; placetin B;plasminogen activator inhibitor; platinum complex; platinum compounds;platinum-triamine complex; porfimer sodium; porfiromycin; prednisone;propyl bis-acridone; prostaglandin J2; proteasome inhibitors; proteinA-based immune modulator; protein kinase C inhibitor; protein kinase Cinhibitors, microalgal; protein tyrosine phosphatase inhibitors; purinenucleoside phosphorylase inhibitors; purpurins; pyrazoloacridine;pyridoxylated hemoglobin polyoxyethylene conjugate; raf antagonists;raltitrexed; ramosetron; ras farnesyl protein transferase inhibitors;ras inhibitors; ras-GAP inhibitor; retelliptine demethylated; rhenium Re186 etidronate; rhizoxin; ribozymes; RII retinamide; rogletimide;rohitukine; romurtide; roquinimex; rubiginone B1; ruboxyl; safingol;saintopin; SarCNU; sarcophytol A; sargramostim; Sdi 1 mimetics;semustine; senescence derived inhibitor 1; sense oligonucleotides;signal transduction inhibitors; signal transduction modulators; singlechain antigen binding protein; sizofuran; sobuzoxane; sodiumborocaptate; sodium phenylacetate; solverol; somatomedin bindingprotein; sonermin; sparfosic acid; spicamycin D; spiromustine;splenopentin; spongistatin 1; squalamine; stem cell inhibitor; stem-celldivision inhibitors; stipiamide; stromelysin inhibitors; sulfinosine;superactive vasoactive intestinal peptide antagonist; suradista;suramin; swainsonine; synthetic glycosaminoglycans; tallimustine;5-fluorouracil; leucovorin; tamoxifen methiodide; tauromustine;tazarotene; tecogalan sodium; tegafur; tellurapyrylium; telomeraseinhibitors; temoporfin; temozolomide; teniposide; tetrachlorodecaoxide;tetrazomine; thaliblastine; thiocoraline; thrombopoietin; thrombopoietinmimetic; thymalfasin; thymopoietin receptor agonist; thymotrinan;thyroid stimulating hormone; tin ethyl etiopurpurin; tirapazamine;titanocene bichloride; topsentin; toremifene; totipotent stem cellfactor; translation inhibitors; tretinoin; triacetyluridine;triciribine; trimetrexate; triptorelin; tropisetron; turosteride;tyrosine kinase inhibitors; tyrphostins; UBC inhibitors; ubenimex;urogenital sinus-derived growth inhibitory factor; urokinase receptorantagonists; vapreotide; variolin B; vector system, erythrocyte genetherapy; thalidomide; velaresol; veramine; verdins; verteporfin;vinorelbine; vinxaltine; VITAXIN™ (see U.S. Patent Pub. No. US2002/0168360 A1, dated Nov. 14, 2002, entitled “Methods of Preventing orTreating Inflammatory or Autoimmune Disorders by Administering Integrinavf33 Antagonists in Combination With Other Prophylactic or TherapeuticAgents”); vorozole; zanoterone; zeniplatin; zilascorb; and zinostatinstimalamer.

5.7 Vaccine Formulations

In another embodiment, a therapeutic agent capable of ablating theregulatory B cell subset can be administered in conjunction with avaccine in order to increase the immune response associated with aninfectious disease or cancer-associated target, e.g., a tumor orantigen. According to this embodiment, ablation of the regulatory B cellsubset serves to decrease endogenous levels of IL-10 in the subjectbeing vaccinated and to thereby boost the immune response directed tothe infectious agent, infected cells, or tumor antigen. Any infectiousdisease or malignant cell can be vaccinated against according to thismethod of the invention.

A non-limiting list of FDA licensed vaccines (and associated disease)that could be administered in accordance with the methods of theinvention includes: Acel-Immune (Diphtheria, tetanus, pertussis), ActHIB(Haemophilus influenzae type b), Anthrax vaccine, Attenuvax (Measles),Biavax II (Rubella, Mumps), Botox (Botulism), Chickenpox vaccine,Cholera vaccine, Comvax (Haemophilus influenzae type b, Hepatitis B),DTP (Diphtheria, Tetanus, Pertussis), Diphtheria vaccine, Engerix-B(Hepatitis B), Influenza vaccine, Fluvirin (Influenza), German Measlesvaccine, Havrix (Hepatitis A), HBIG (Hepatitis B), Hepatitis A vaccine,Hepatitis B vaccine, Heptavax (Hepatitis B), HibTITER (Haemophilusinfluenzae type b, Diphtheria), Imovax Rabies vaccine, Infanrix(Diphtheria, Tetanus, Pertussis), Ipol (Polio), JE-Vax (JapaneseEncephalitis Virus), Pedvax-HIB (Haemophilus influenzae type b,Meningitis), Meningococcal polysaccharide vaccine (Meningitis),Menomune-A/C/Y/W-135 (Meningitis), Meruvax-II (Rubella), M-M-R II(Measles, Mumps, Rubella), M-R-VAX II (Measles, Mumps, Rubella),Mumpsvax (Mumps), OmniHIB (Haemophilus influenzae type b, Diphtheria),Orimune (Polio), Paratyphoid vaccine (Typhoid), Pertussis vaccine,Plague vaccine, Pneumococcal vaccine (Pneumonia), Pneumovax 23(Pneumonia), Pne-Imune 23 (Pneumonia), Polio vaccine, Recombivax HB(Hepatitis B), RhoGAM (Rhesus), Rocky Mountain Spotted Fever vaccine,Rubella vaccine, Rubeola vaccine, Smallpox vaccine, Tetanus vaccine,Tetramune (Diphtheria, Tetanus, Pertussis, Haemophilus influenzae typeb), Tice BCG USP (Mycobacterium Bovis Infection), Tri-Immunol(Diphtheria, Tetanus, Pertussis), Tripedia (Diphtheria, Tetanus,Pertussis), Typhim Vi (Typhoid), Typhoid vaccine, Typhus vaccine, Vaqta(Hepatitis A), Varicella vaccine, Varivax (Varicella), Vivotif Berna(Typhoid), and Yellow Fever vaccine.

In one aspect of this embodiment, the therapeutic agent capable ofablating the regulatory B cell subset and the vaccine are administeredconcurrently. In another aspect of this embodiment, the therapeuticagent capable of ablating the regulatory B cell subset is administeredprior to administration of the vaccine. Alternatively, the therapeuticagent capable of ablating the regulatory B cell subset can beadministered following the administration of the vaccine.

In another aspect of this embodiment, the therapeutic agent capable ofablating the regulatory B cell subset and the vaccine are administeredin conjunction with an adjuvant. A non-limiting list of adjuvantsadministered in accordance with the methods of the invention includes:alum (e.g., aluminum hydroxide, aluminum phosphate); Montanide ISA 720;MF-59; PROVAX; immunostimulatory nucleic acids, such as CpGoligodeoxynucleotides; saponins purified from the bark of the Q.saponaria tree, such as QS21; poly[di(carboxylatophen-oxy)phosphazene,derivatives of lipopolysaccharides (LPS), such as monophosphoryl lipidA, muramyl dipeptide (MDP; Ribi) andthreonyl-muramyl dipeptide (t-MDP;Ribi); OM-174; Leishmania elongation factor; ISCOMs; SB-AS2; SB-AS4;non-ionic block copolymers that form micelles such, as CRL 1005; SyntexAdjuvant Formulation CpG nucleic acids; Bacterial toxins, e.g., Choleratoxin (CT), CT derivatives including but not limited to CT B subunit(CTB); Zonula occludens toxin, zot; Escherichia coli heat-labileenterotoxin; Labile Toxin (LT), LT derivatives including but not limitedto LT B subunit (LTB); Pertussis toxin, PT; toxin derivatives; Lipid Aderivatives (e.g., monophosphoryl lipid A, MPL); bacterial outermembrane proteins (e.g., outer surface protein A (OspA) lipoprotein ofBorrelia burgdorferi, outer membrane protein of Neisseria meningitidis).

5.8 Diagnostics

In another embodiment, methods are provided for diagnosing a subjectsuffering from a disease that is associated with elevated or diminishedlevels of IL-10 production. In another embodiment, a subject with apredisposition to a certain disease can be diagnosed. In an aspect ofthese embodiments, regulatory B cells are isolated from the subject andassayed for specificity to a certain disease-specific antigen.

The regulatory B cells to be analyzed may be collected from any locationin which they reside in the subject including, but not limited to,blood, spleen, thymus, lymph nodes, and bone marrow. The isolatedregulatory B cells may be analyzed intact, or lysates may be preparedfor analysis.

Methods for the quantitation of cells and detection of antigenicspecificity are known in the art, and may include pre-labeling thesample directly or indirectly; adding a second stage antibody that bindsto the antibodies or to an indirect label, e.g., labeled goat anti-humanserum, rat anti-mouse, and the like. For example, see U.S. Pat. No.5,635,363. Generally, assays will include various negative and positivecontrols, as known in the art.

Various methods are used to determine the antigenic specificity profilefrom a patient sample. The comparison of a binding pattern obtained froma patient sample and a binding pattern obtained from a control, orreference, sample is accomplished by the use of suitable deductionprotocols including, but not limited to, AI systems, statisticalcomparisons, and pattern recognition algorithms. Typically a data matrixis generated, where each point of the data matrix corresponds to areadout from a specific epitope. The information from reference patternscan be used in analytical methods to determine relative abundance,changes over time, and any other factors relevant to analysis.

Any disease can be diagnosed according to these embodiments. Inparticular, diseases associated with diminished levels of endogenousIL-10, i.e., immune and inflammatory diseases, and diseases associatedwith elevated levels of endogenous IL-10, i.e., cancer can be diagnosedbased on isolation of regulatory B cells in a subject withdisease-specific antigen specificity.

In another embodiment, a subject diagnosed with a given disease can bemonitored for disease progression. Formats for patient sampling includetime courses that follow the progression of disease, comparisons ofdifferent patients at similar disease stages, e.g., early onset, acutestages, recovery stages; and tracking a patient during the course ofresponse to therapy. In an aspect of this embodiment, the numbers ofregulatory B cells having specificity to a certain disease-specificantigen can be monitored over the course of a given therapy. As anon-limiting example, a therapy designed to expand the endogenouspopulation of regulatory B cells that respond to a given disease shouldresult in an increase in the numbers of regulatory B cells withspecificity to a certain antigen associated with said disease relativeto the general population of regulatory B cells.

6. EXAMPLE 1 A Regulatory B Cell Subset with a Unique CD1D^(HIGH) CD5⁺Phenotype Controls T Cell-Dependent Inflammatory Responses

B cells mediate multiple functions that influence immune andinflammatory responses. In this study, T cell-mediated inflammation wasexaggerated in CD19-deficient mice and mice depleted of CD20⁺ B cells,while inflammation was significantly reduced in mice with hyperactivatedB cells due to CD19 overexpression (hCD19Tg). These inflammatoryresponses were negatively regulated by a unique spleen CD1d^(high)CD5⁺ Bcell subset that was absent in CD19^(−/−) mice, represented only 1-2% ofspleen B220⁺ cells in wild type mice, but was expanded to ˜10% of B220⁺cells in hCD19Tg mice. Adoptive transfer of these spleen CD1d^(high)CD5⁺B cells normalized the exacerbated inflammation observed in wild typemice depleted of CD20⁺ B cells and in CD19^(−/−) mice. Remarkably, IL-10production was restricted to this CD1d^(high)CD5⁺ B cell subset, withIL-10 production diminished in CD19^(−/−) mice, yet increased in hCD19TGmice. Thereby, CD1d^(high)CD5⁺ B cells represent a novel and potentsubset of regulatory B cells.

6.1 Materials and Materials

6.1.1 Abs and Immunofluorescence Analysis

Mouse CD20-specific mouse mAb MB20-11 (IgG2c) was used as described(Uchida et al., 2004, J. Exp. Med. 199:1659-69). The mouse anti-humanCD19 (hCD19) mAb FMC63 (IgG2a, provided by Dr. Heddy Zola, Child HealthResearch Inst., Adelaide, South Australia) was used as described (YazaWaet al., 2005, Proc. Natl. Acad. Sci. USA 102:15178-83). Other mAbsincluded: B220 mAb RA3-6B2 (provided by Dr. Robert Coffman, DNAX Corp.,Palo, Alto, Calif.); CD19 (1D3), CD5 (53-7.3), CD1d (1B1), CD21/35(7G6), CD23 (B3B4), CD24 (M1/69), CD25 (PC61), CD43 (S7), and CD11b(M1/70) from BD PharMingen (San Diego, Calif.); IgM (11/41) fromeBioscience (San Diego, Calif.); and IgD (11-26) from SouthernBiotechnology Associates (Birmingham, Ala.). Intracellular staining forFoxp3 (FJK-16s, eBioscience) used the Cytofix/Cytoperm kit (BDPharMingen). Single cell suspensions of spleen, peripheral lymph node(cervical, paired axillary and inguinal), and mesenteric lymph node weregenerated by gentle dissection. To isolate peritoneal cavity leukocytes,10 ml of cold (4° C.) PBS was injected into the peritoneum of sacrificedmice followed by gentle massage of the abdomen. Intestinal Peyer'spatches were isolated as described (Venturi et al., 2003, Immunity19:713-24). Peripheral blood mononuclear cells were isolated fromheparinized blood after centrifugation over a discontinuous Lymphoprep(Axis-Shield PoC As, Oslo, Norway) gradient. Viable cells were countedusing a hemocytometer, with relative lymphocyte percentages determinedby flow cytometry analysis. Single-cell leukocyte suspensions werestained on ice using predetermined optimal concentrations of eachantibody for 20-60 min, and fixed as described (Sato et al., 1996, J.Immunol. 157:4371-8). Cells with the light scatter properties oflymphocytes were analyzed by 2-4 color immunofluorescence staining andFACScan or FACSCalibur flow cytometers (Becton Dickinson, San Jose,Calif.). Background staining was determined using unreactiveisotype-matched control mAbs (Caltag Laboratories, San Francisco,Calif.) with gates positioned to exclude ≧98% of unreactive cells.,

6.1.2 Mice and Immunotherapy

Wild-type C57BL/6 and IL-10^(−/−) (B6.129P2-Il10^(tmlGcg)/J) mice (Kuhnet al., 1993, Cell 75:263-74) were from The Jackson Laboratory (BarHarbor, Me.). CD20^(−/−), CD19^(−/−), and hCD19Tg (h19-1 line) mice wereas described (Sato et al., 1996, J. Immunol. 157:4371-8; Sato et al.,1997, J. Immunol. 158:4662-9; Uchida et al., 2004, Int. Immunol.16:119-29). Specifically, CD19^(−/−) and hCD19Tg mice were backcrossedwith C57BL/6 mice for 14 and 7 generations, respectively.

To deplete B cells, sterile CD20, hCD19, and isotype-matched controlmAbs (250 μg) were injected in 200 μl PBS through lateral tail veins.All mice were bred in a specific pathogen-free barrier facility and usedat 8-12 wks of age.

6.1.3 Contact Hypersensitivity Reaction

CHS reactions were induced using oxazolone as described (Tedder et al.,1995, J. Exp. Med. 181:2259-64). Briefly, mice were sensitized with 25μl of a solution consisting of oxazolone (100 mg/ml,4-ethyoxymethylene-2-phenyloxazolone; Sigma, St. Louis, Mo.) inacetone/olive oil (4:1 v/v) applied evenly for two consecutive days on ashaved hind flank. On day 5, sensitized mice were challenged by applying10 μl of oxazolone solution (10 mg/ml) in acetone/olive oil (4:1) to theright ear (5 μl on the dorsal side and 5 μl on the ventral side). Incertain experiments, 25 μl of 0.5% 2,4-dinitrofluorobenzene (DNFB,Sigma) was used as the sensitization agent. An identical amount ofacetone/olive oil (4:1) was administered to the left ear. In someexperiments, mice were treated with 250 μg anti-IL-10 receptor (1B1.3a;BD PharMingen) or isotype control mAb 1 hour before and 47 hours afteroxazolone challenge. The thickness of the central portion of each earlobe was measured at 24, 48, 72, and 96 hours after challenge using aconstant force, calibrated digital thickness gage (Mitsutoyo Corp.,Tokyo, Japan). Each ear lobe was measured three times at each timeinterval in a blinded fashion, with the mean of these values used foranalysis.

6.1.4 B Cell Isolation and Stimulation

B220- or CD19-mAb coated microbeads (Miltenyi Biotech, Auburn, Calif.)were used to purify B cells by positive selection following themanufacturer's instructions. When necessary, the cells were enriched asecond time using a fresh MACS column to obtain >95% purities.

For cytokine production, 4×10⁵ purified B cells were cultured eitherwith LPS (10 Escherichia coli serotype 0111: B4, Sigma) or with goatF(ab′)₂ anti-mouse IgM antibody (20 μg/ml, Cappel, Aurora, Ohio) plusCD40 mAb (1 μg/ml, HM40-3; BD PharMingen) in 0.2 ml of complete medium(RPMI 1640 media containing 10% FCS, 200 μg/ml penicillin, 200 U/mlstreptomycin, 4 mM L-Glutamine, and 5×10⁻⁵ M 2-mercaptoethanol; all fromGibco, Carlsbad, Calif.) in a 96-well flat-bottom plate for 48 h.Culture supernatant fluid was collected after 48 hours to assesscytokine production.

6.1.5 Cytokine Analysis Using ELISA and Luminex Assays

Cytokines were measured in culture supernatant fluid using theFluorokine MAP multiplex kit (R&D Systems, Minneapolis, Minn.) withLuminex® 100TH dual laser, flow-based sorting and detection (LuminexCorporation, Austin, Tex.) allowing simultaneous quantification of thefollowing cytokines in single samples: IL-10, IL-4, IL-5, IL-6, IL-10IL-12, IL-13, IL-17, TNF-α, IFN-γ, and GM-CSF: Cytokine concentrationsin culture supernatant fluid were also quantified using IL-10 OptEIAELISA kits (BD PharMingen), IL-23 (p19/p40) ELISA Ready-SET-Go kits(eBioscience), and TGF-131 DuoSet kits (R&D Systems) following themanufacturer's protocols. All assays were carried out on triplicatesamples.

6.1.6 ELISPOT

The frequency of IL-10-producing B cells was determined using ELISPOTassays as described (Morris et al., 1994, J. Immunol. 152:1047-56).Briefly, Immobilon-P Multiscreen 96-well plates (Millipore, Billerica,Mass.) were precoated with 100 μl of capture mAb (JES5-2A5, 5 μg/ml) at4° C. overnight. After three PBS washes, plates were blocked withcomplete medium (200 μl/ml) for 2 hours at room temperature. Purified Bcells in 100 μl complete medium containing LPS (10 μg/ml) were culturedin the coated plates in duplicate at 37° C. in a humidified CO₂incubator for 24 h. After washing, biotinylated detection mAb (SXC-1, 2μg/ml, BD PharMingen) was added to the wells (100 μl/well). Afterincubation for 2 hours at room temperature, the plates were washed,streptavidine-HRP (BD PharMingen) was added to the wells, and the plateswere incubated for 1 hour at room temperature. After washing, the plateswere developed using 3-amino-9-ethylcarbazone and H₂O₂ (BD PharMingen).

6.1.7 Flow Cytometric Analysis of Intracellular IL-10 Synthesis

Intracellular cytokine analysis was as described (Openshaw et al., 1995,J. Exp. Med., 182:1357-67). Briefly, isolated leukocytes or purifiedcells were resuspended (1×10⁶ cells/ml) with LPS (10 μg/ml), PMA (50ng/ml; Sigma), ionomycin (500 ng/ml; Sigma), and monensin (2 μM;eBioscience) for 5 h. For IL-10 detection, Fc receptors were blockedwith anti-mouse Fc receptor mAb (2.4G2; BD PharMingen) before cellsurface staining, and then fixed and permeabilized using theCytofix/Cytoperm kit (BD PharMingen) according to the manufacturer'sinstructions. Permeabilized cells were stained withphycoerythrin-conjugated anti-IL-10 mAb (JES5-16E3; BD PharMingen).Leukocytes from IL-10^(−/−) mice served as negative controls todemonstrate specificity and to establish background-staining levels.

6.1.8 Isolation of Total RNA and Real-Time Reverse Transcription PCR

B cells were purified (>95% purity) using B220 mAb-coated magneticbeads. Total RNA was extracted using TRIzol (Invitrogen, Carlsbad,Calif.). Random hexamer primers (Promega, Madison, Wis.) and SuperscriptII RNase H Reverse Transcriptase (Invitrogen, Carlsbad, Calif.) wereused to generate cDNA as described (Engel et al., 1993, J. Immunol.150:4719-32). IL-10 transcripts were quantified by real-time PCRanalysis using SYBR Green as the detection agent as described (Ponomarevet al., 2004, J. Immunol. 173:1587-95). The PCR was performed with theiCycler iQ system (Bio-Rad, Hercules, Calif.). All components of the PCRmix were purchased from Bio-Rad and used according to the manufacturer'sinstructions. Cycler conditions were one amplification cycle ofdenaturation at 95° C. for 3 min followed by 40 cycles of 95° C. for 10s, 59° C. for 1 min, and 95° C. for 1 min. Specificity of the RT-PCR wascontrolled by the generation of melting curves. IL-10 expressionthreshold values were normalized to GAPDH expression using standardcurves generated for each sample by a series of four consecutive 10-folddilutions of the cDNA template. For all reactions, each condition wasperformed in triplicate. Data analysis was performed using iQ Cycleranalysis software. The sense IL-10 primer was 5% GGTTGCCAAGCCTTATCGGA-3′and the antisense primer was 5′-ACCTGCTCCACTGCCTTGCT-3′. The sense GAPDHprimer was 5′-TTCACCACCA TGGAGAAGGC-3′ and the antisense primer was5′-GGCATGGACTGTGGTCATGA-3′ (Ponomarev et al., 2004, J. Immunol.173:1587-95).

6.1.9 Microarray Expression Profiling

For microarray analysis, viable IL-10 secreting B cells were detectedafter 5 hours of LPS, PMA, and ionomycin stimulation using an IL-10secretion detection kit (Miltenyi Biotech) before cell sorting. RNAsfrom purified B cell subsets were prepared as above and processed foruse on Affymetrix Mouse Genome 430 2.0 GeneChips (Affymetrix, SantaClara, Calif.). All quality parameters for the arrays were confirmed tobe in the range recommended by the manufacturer.

6.1.10 Cell Sorting and Adoptive Transfers

Splenic B cells were purified using CD19 mAb-coupled microbeads(Miltenyi Biotech). In addition, CD1d^(high)CD5⁺ B cells were selectedusing a FACSVantage SE flow cytometer (Becton-Dickinson, San Jose,Calif.) with purities of ˜85%-95%. After isolation, 2×10⁶CD1d^(high)CD5⁺ or non-CD1d^(high)CD5⁺ B cells were immediatelytransferred i.v. into CD19^(−/−) or B cell-depleted recipient micebefore CHS induction.

6.1.11 Statistical Analysis

All data are shown as means±SEM. The significance of differences betweensample means was determined using the Student's t test.

6.2 Results

6.2.1 Mice with Altered B Cells Differentially Regulate Inflammation

To assess T cell-mediated inflammation responses in mice with altered Bcell signaling, CD19^(−/−) hCD19Tg, and their wild type littermates weresensitized and challenged with oxazolone. B cells from hCD19Tg mice arehyper-responsive to transmembrane signals, proliferate at higher levelsto certain mitogens, generate elevated humoral immune responses toT-dependent antigens, and spontaneously produce increasing amounts ofIgG subclass auto-Abs as they age (Inaoki et al., 1997, J. Exp. Med.186:1923-31). Thus, CD19 functions as a general ‘rheostat’ that definessignaling thresholds critical for expansion of the peripheral B cellpool (Tedder, 1998, Semin. Immunol. 10:259-65). Ear inflammation wasmeasured before and every 24 hours after challenge. In wild type mice,ear inflammation peaked at 24 hours after challenge, then decreasedgradually (FIG. 1A). Ear swelling was significantly diminished inhCD19Tg mice compared with wild type littermates throughout theobservation period (39±13%, 48 h, p<0.05). By contrast, ear swelling wasenhanced and prolonged in CD19^(−/−) mice (58±8%, 48 h, p<0.05) asreported (Watanabe et al., 2007, Am. J. Pathol. 171:560-70). Despitethis, blood, spleen, and lymph node regulatory CD25⁺Foxp3⁺CD4⁺ T cellnumbers were identical in wild type, hCD19Tg, and CD19^(−/−) mice. Thus,enhanced or reduced B cell function inversely paralleled T cell-mediatedinflammatory responses.

6.2.2 B Cell Depletion Enhances CHS Responses

To determine whether B cells were directly responsible for decreased Tcell-mediated inflammatory responses in hCD19Tg mice, B cells weredepleted in hCD19Tg mice by using anti-human CD19 mAb as described(Yazawa et al., 2005, Proc. Natl. Acad. Sci. USA 102:15178-83). CD19mAbs depleted the vast majority of circulating B cells within 1 hour oftreatment, with >95% depletion of spleen and lymph node B cells within 2days. Mice were treated with a single injection of hCD19 mAb 7 daysbefore or 2 days after primary oxazolone sensitization. Mice treatedwith hCD19 mAb 7 days before primary sensitization showed significantlyenhanced CHS responses compared with control mAb-treated littermates(p<0.01, FIG. 1B). Mice treated with hCD19 mAb 2 days after primaryoxazolone sensitization had comparable CHS responses with controlmAb-treated mice at 24 hours following oxazolone elicitation, butdeveloped augmented CHS responses by 48 hours after elicitation. Earswelling 48 hours after oxazolone challenge in mice treated with hCD19mAb 7 days before or 2 days after primary oxazolone sensitization wasincreased by 102±8% or 89±12%, respectively. Thus, B cell depletion inhCD19Tg mice restored CHS responses to levels observed in wild typelittermates.

To examine whether normal B cells regulate T cell-mediated inflammatoryresponses in wild type mice, B cells were depleted from mice with intactimmune systems using CD20 mAb. Mature CD20⁺ B cells in wild type miceare eliminated within 2 days after a single treatment with CD20 mAb(Uchida et al., 2004, J. Exp. Med. 199:1659-69). Mice depleted of Bcells 7 days before or 2 days following primary oxazolone sensitizationexhibited significantly enhanced CHS responses when compared withcontrol mAb-treated littermates: 91±10% and 72±11% increase,respectively at 48 hours after oxazolone challenge (FIG. 1C). Thus, Bcell depletion augmented T cell-mediated inflammatory responses in bothwild type and hCD19Tg mice.

To determine whether CD19-deficiency completely eliminates B cellnegative regulation, CD19^(−/−) mice were also depleted of B cells usingCD20 mAb. B cell depletion further increased CHS severity in CD19^(−/−)mice, but the difference was not statistically different from controlmAb-treated littermates (FIG. 1D). This suggests that some regulatory Bcells still exist in CD19^(−/−) mice, but at levels below those found inwild type and hCD19Tg mice. Moreover, anti-human CD19 as well asanti-mouse CD20 mAbs do not eliminate all peritoneal cavity B cells inthese short-term experiments (Hamaguchi et al., 2005, J. Immunol.7:4389-99; Yazawa et al., 2005, Proc. Natl. Acad. Sci. USA102:15178-83). Furthermore, CD20 mAb treatment does not reduce serum ornatural Ab levels (DiLillo et al., 2008, J. Immunol. 180:361-71).Thereby, induced B cell depletion eliminates most B cell negativeregulation, but does not eliminate the peritoneal B-1 cell populationthat also appears important for CHS initiation (Itakura et al., 2005, J.Immunol. 175:7170-8).

6.2.3 B Cell Cytokine Expression in Wild Type, hCD19Tg, and CD19^(−/−)Mice

B cells produce multiple cytokines that can act as growth anddifferentiation factors and influence immune responses (Harris et al.,2000, Nat. Immunol. 1:475-82). Therefore, B cells were purified fromwild type, hCD19Tg, and CD19^(−/−) mice (FIG. 2A) with cytokineproduction quantified and compared with T cell-mediated inflammatoryresponses observed in each mouse strain. While B cells cultured withoutmitogens did not produce cytokines, lipopolysaccharide (LPS)-stimulatedB cells from wild type, hCD19Tg, and CD19^(−/−) mice producedsignificant levels of TNF-α, IL-β, IL-10, and IL-6 protein as determinedusing Luminex assays (FIG. 2B). Anti-IgM antibody plus CD40 mAbstimulation also induced the production of these cytokines, but at lowerlevels than induced by LPS stimulation. Only wild type B cells secretedTGF-β1, but only at very low levels after anti-IgM antibody plus CD40mAb stimulation. Neither LPS nor anti-IgM antibody plus CD40 mAbstimulation induced detectable IL-4, -5, -12, -13, -17, or -23secretion. Nonetheless, increased and decreased IL-10 production by Bcells was the only cytokine change that paralleled the decreased andincreased inflammatory responses of hCD19Tg and CD19^(−/−) mice,respectively. In Luminex and standard ELISAs, B cells from hCD19Tg miceshowed increased IL-10 levels compared with wild type mice (LPSstimulation 1.8-fold; p<0.01), while B cells from CD19^(−/−) miceexhibited reduced IL-10 levels (65% of wild type, p<0.05; FIG. 2B-C).Using ELISPOT assays, IL-10-producing B cell frequencies were 2.7-foldhigher in hCD19Tg mice than wild type mice (p<0.01), but 74% lower inCD19^(−/−) mice than in wild type mice (p<0.01; FIG. 2D). Thus,increased and decreased frequencies of IL-10-producing B cellsparalleled the decreased and increased inflammatory responses of hCD19Tgand CD19^(−/−) mice, respectively.

6.2.4 IL-10-Producing B Cells Localize in the Spleen and PeritonealCavity

Reciprocal IL-10 production by B cells from hCD19Tg and CD19^(−/−) micewas verified directly by intracellular cytokine staining. CytoplasmicIL-10 production was not detected in resting B cells from wild type,hCD19Tg, or CD19^(−/−) mice (FIG. 3A). After stimulation with LPS, PMA,and ionomycin for 5 h, the frequencies of spleen IL-10-producing B cellswas 7.4-fold higher in hCD19Tg mice than in wild type mice (p<0.01),whereas the frequency of IL-10-producing B cells was 85% lower inCD19^(−/−) mice than in wild type mice (p<0.01; FIG. 3B). Interestingly,IL-10 production by non-B cells after LPS, PMA, and ionomycinstimulation was also increased in hCD19Tg mice (FIG. 4). In addition,constitutive CD19 overexpression by B cells since birth can affect Tcell activation independent of immunization (Stohl et al., 2005, Clin.Immunol. 116:257-64), suggesting additional inhibitory mechanisms inthese mice as a potential result of B cell hyperactivity. PeritonealIL-10-producing B cell frequencies were 3-fold higher in hCD19Tg micethan in wild type mice (p<0.01), but 80% lower in CD19^(−/−) mice(p<0.01; FIG. 3C). Even though both CD19^(−/−) and hCD19Tg mice havesignificantly reduced numbers of splenic B cells compared with wild typemice (Haas et al., 2005, Immunity 23:7-18; Sato et al., 1997, J.Immunol. 158:4662-9; Sato et al., 1995, J. Immunol. 157:4371-8), thenumbers of IL-10-producing splenic and peritoneal B cells were 2.1-foldand 3.1-fold higher in hCD19Tg mice than in wild type mice, respectively(p<0.01). Splenic and peritoneal IL-10-producing B cell numbers were 80%and 78% lower in CD19^(−/−) mice than in wild type mice, respectively(p<0.01). By contrast, naïve or stimulated B cells from blood,peripheral and mesenteric lymph nodes, and Peyer's patches exhibitedlittle, if any, IL-10 production in wild type, hCD19Tg, or CD19^(−/−)mice (FIG. 3D-F). Intracellular staining of B cells from IL-10^(−/−)mice served as background controls. Thus, IL-10-producing B cellsrepresent a distinct subset that was dramatically reduced in CD19^(−/−)mice, but preferentially expanded in hCD19Tg mouse spleen and peritonealcavity.

6.2.5 Cytokine gene expression by IL-10 producing B cells

Whether IL-10-producing B cells preferentially generated other cytokinetranscripts was examined by microarray analysis of purifiedIL-10-secreting B cells relative to other spleen B cells from hCD19Tgmice (FIG. 3G). IL-10-secreting B cells exhibited 6-fold higher levelsof IL-10 transcripts when compared with other B cells, whereastranscript levels were not significantly different for all othercytokines (FIG. 3H). Thus, IL-10-secreting B cells were unique in theircytokine production capability.

6.2.6 Spleen IL-10-Producing B Cells are CD1d^(high)CD5⁺

Whether IL-10-producing B cells represent a known B cell subset wasdetermined by immunofluorescence staining with flow cytometry analysis.Since B cell cytoplasmic IL-10 was only visualized after combined LPS,PMA, ionomycin, and monensin treatment for 5 hours (FIG. 3), the effectof this treatment and cell permeabilization on phenotypes wasdetermined. In all cases, untreated, treated, or permeabilized B cellsfrom wild type and hCD19Tg mice expressed identical IgM, IgD, CD19, CD5,CD1d, CD21, CD24, CD23, CD11b, CD43, and B220 densities (FIG. 5A). Itwas therefore possible to use these cell surface molecules to categorizeIL-10-producing B cells. Spleen IL-10-producing B cells in wild type andhCD19Tg mice were part of a mouse CD19^(high) subset (FIG. 3B-C).Furthermore, spleen IL-10-producing B cells exhibited theCD5⁺CD19^(high) phenotype characteristic of B-1a cells, but unexpectedlyexpressed high CD levels in both wild type and hCD19Tg mice (FIG. 5B).By contrast, CD19^(−/−) mice did not have detectable spleenCD1d^(high)CD5⁺ or IL-10-producing B cells (FIGS. 3B and 5C, Table I).On average, B cells with a CD1d^(high)CD5⁺ phenotype represented 2.3%and 12.2% of spleen B220⁺ cells in wild type and hCD19Tg mice,respectively (FIG. 6C). The number of CD1d^(high)CD5⁺ splenic B cellswas 38% higher in hCD19Tg mice than in wild type mice (Table I).CD1d^(high)CD5⁺ B cells did not express IL-10 at significant frequencies(FIG. 6C). Within the CD1d^(high)CD5⁺ B cell subset, an average of 18%and 58% expressed IL-10 in wild type and hCD19Tg mice, respectively.When CD1d^(high)CD5⁺ or the remaining spleen B cells were purified andthen stimulated, the vast majority of IL-10 producing B cells were foundwithin the CD1d^(high)CD5⁺ subset of B cells from wild type and hCD19Tgmice (FIG. 6D), further excluding the possibility that LPS, PMA, andionomycin treatment induced their phenotype as well as IL-10 production.

To further verify the phenotype of IL-10-producing spleen B cells, thephenotype of the IL-10⁺ and IL-10⁻ populations was determined. Mostsplenic IL-10-producing B cells expressed IgM, CD1d, CD19, and CD24 athigh levels (FIG. 5B, 5E). Approximately half of splenic IL-10-producingB cells expressed high density CD21 (44.3±2.6% and 54.8±1.6% in wildtype and hCD19Tg mice, respectively). Peritoneal cavity IL-10-producingB cells were CD19^(high) IgM^(high) CD5⁺CD23⁻ CD11b⁺ CD43⁺ B220^(low), aphenotype consistent with B-1a cells. Thus, splenic IL-10-producing Bcells shared features common to marginal zone (MZ), T2-MZ precursors,and B-1a B cells, but were localized within a unique CD1d^(high)CD5⁺subset.

6.2.7 Increased B Cell IL-10 Expression During T Cell-Mediated Responses

To determine whether B cell IL-10 production might contribute toregulation of T cell-mediated inflammation, IL-10 production by B cellswas assessed during CHS responses in wild type, hCD19Tg, or CD19^(−/−)mice. Spleen and draining axillary and inguinal lymph node B cells werepurified two days after ear challenge with oxazolone, with IL-10 mRNAlevels quantified by real-time PCR analysis. Relative IL-10 transcriptlevels in B cells from spleen and peripheral lymph nodes of unchallengedhCD19Tg mice were significantly increased relative to B cells from wildtype mice (spleen 4.5-fold, p<0.01, lymph node 1.5-fold, p<0.05; FIG.6A). During CHS responses, spleen B cells from both wild type andhCD19Tg mice exhibited significantly higher IL-10 transcript levels thannaïve B cells (6-fold, p<0.01 and 2.2-fold, p<0.01, respectively), andhCD19Tg B cells produced significantly higher IL-10 transcripts thanwild type B cells (1.8-fold, p<0.01; FIG. 6A, left panel). IL-10transcript levels in spleen B cells from challenged CD19^(−/−) miceincreased significantly during CHS responses but only up to 16% oflevels from wild type B cells (p<0.01). By contrast, B cell IL-10 mRNAlevels in draining lymph nodes did not change during CHS responses (FIG.6A, right panel). In similar experiments, IL-10 transcripts produced bythe spleen CD1d^(high)CD5⁺ B cell subset were increased 7.1-fold duringCHS responses in comparison with naïve CD1d^(high)CD5⁺ B cells, whileIL-10 transcript levels were significantly lower in non-CD1d^(high)CD5⁺B cells with or without sensitization and challenge (FIG. 6B). Thus, Bcell IL-10 production in the spleen but not lymph nodes was increasedduring CHS responses and the level of IL-10 production by B cellsinversely paralleled the severity of inflammatory responses.

6.2.8 IL-10 Inhibits T Cell-Mediated Inflammatory Responses in hCD19Tgand Wild Type Mice

Blocking IL-10 function in vivo using an anti-IL-10 receptor mAbenhances CHS responses in wild type mice (Ferguson et al., 1994, J. Exp.Med. 179:1597-1604). Therefore, whether the enhanced CHS responsesobserved in hCD19Tg mice were dependent on IL-10 was assessed using afunction-blocking mAb reactive with the IL-10 receptor (Barrat et al.,2002, J. Exp. Med. 195:603-16). Anti-IL-10 receptor mAb treatment 1 hourbefore oxazolone challenge significantly augmented CHS responses inhCD19Tg mice when compared with control mAb-treated littermates (FIG.6C, p<0.05 at 48 h). In fact, anti-IL-10 receptor mAb treatment restoredCHS responses to levels normally observed in wild type littermates.Thus, the suppression of T cell-mediated inflammation observed inhCD19Tg mice was IL-10 dependent.

The relative contribution of wild type IL-10-producing B cells to CHSsuppression was assessed by comparing the effects of CD20 mAb-induced Bcell depletion in wild type and IL-10^(−/−) mice. B cell depletionsignificantly augmented CHS responses in wild type mice (FIG. 6D).Remarkably, CHS responses were increased similarly by B cell depletionand IL-10-deficiency after 24 hours after challenge. Subsequently, CHSresponses were higher in mice, suggesting that B cell IL-10 productioncontributed most significantly to early inhibition of CHS responses,while IL-10 production by the remaining peritoneal B cells or otherIL-10 producing subsets regulated later stages of the CHS response.Equally important was that CD20 mAb-induced B cell depletion did notaffect CHS severity in IL-10^(−/−) mice, arguing that the inhibitoryrole of B cells in CHS regulation is solely due to IL-10 production.Thus, B cells suppressed T cell-mediated inflammation in anIL-10-dependent manner, with a more significant contribution earlyduring inflammation.

IL-10-production by blood B cells was also assessed to determine whetherIL-10-producing B cells enter the circulation during CHS responses.IL-10-producing B cells were not observed in IL-10^(−/−) or naïve micebefore oxazolone-sensitization (FIGS. 3D and 6E). However, circulatingIL-10-producing B cells were found in the blood after sensitization,with the percentage of circulating IL-10-produCing B cells peakingbefore challenge and gradually decreasing after challenge (FIG. 6E).Thus, IL-10-producing B cells enter the circulation during CHSresponses.

6.2.9 Adoptive Transfer of CD1d^(high)CD5⁺ B Cells Inhibit TCell-Mediated Inflammatory Responses

The ability of CD1d^(high)CD5⁺ B cells to regulate CHS responses wasassessed using adoptive transfer experiments. Splenic CD 1d^(high)CD5⁺ Bcells and non-CD1d^(high)CD5⁺ B cells were purified from eitheroxazolone-sensitized (5 days after primary sensitization) wild type miceor their unsensitized littermates (FIG. 7A, left panels). Purified Bcells were then transferred into oxazolone-sensitized CD19^(−/−) micethat were challenged with oxazolone 48 hours after the transfer.Sensitized CD1d^(high)CD5⁺ B cells transferred into CD19^(−/−) micesignificantly reduced (43% at 48 h, p<0.05) ear swelling (FIG. 7A,middle panel). Ear swelling was not inhibited in recipients givenCD1d^(high)CD5⁺ B cells from non-sensitized mice or non-CD1d^(high)CD5⁺B cells from sensitized mice. Likewise, splenic CD1d^(high)CD5⁺ B cellspurified from oxazolone-sensitized IL-10^(−/−) mice did not affect earswelling in CD19^(−/−) recipients (FIG. 7A, right panel). Thus,sensitized splenic CD1d^(high)CD5⁺ B cells inhibited CHS responses in anIL-10-dependent manner and likely in an antigen-specific manner.

To assess whether IL-10-producing CD1d^(high)CD5⁺ B cells also played arole in CHS responses in wild type mice, spleen CD1d^(high)CD5⁺ B cellswere purified from oxazolone sensitized CD20^(−/−) mice (FIG. 7B, leftpanels) and transferred into wild type recipient mice that had beendepleted of B cells using CD20 mAb. CD20^(−/−) mice do not express CD20and are therefore resistant to B cell depletion. CD20^(−/−) mice hadnormal numbers of CD1d^(high)CD5⁺ IL-10-producing B cells compared towild type mice. When B cells were depleted in wild type mice, CHSresponses were increased significantly. However, the adoptive transferof sensitized CD1d^(high)CD5⁺CD20^(−/−) B cells just before challengenormalized CHS responses in B cell-depleted mice (FIG. 7B, middlepanel). The adoptive transfer of naïve CD1d^(high)CD5⁺CD20^(−/−) B cellsinto B cell-depleted mice 2 days before oxazolone sensitization and thenear challenge had the same effect (FIG. 7B, right panel). By contrast,the transfer of non-CD1d^(high)CD5⁺CD20^(−/−) B cells from naïve orsensitized mice into recipients before sensitization or challenge,respectively, did not reduce oxazolone-induced ear swelling. Thus, IL-10secretion by CD1d^(high)CD5⁺ B cells regulated T cell-mediatedinflammatory responses in vivo.

Whether IL-10 secretion by CD1d^(high)CD5⁺ B cells was induced byinflammation or was antigen-specific was addressed by the adoptivetransfer of splenic CD1d^(high)CD5⁺ B cells purified fromDNFB-sensitized mice (FIG. 7C, left panels). When transferred intooxazolone-sensitized CD19^(−/−) recipients, neither CD1d^(high)CD5⁺ nornon-CD1d^(high)CD5⁺ B cells purified from DNFB-sensitized mice affectedear swelling in CD19^(−/−) recipients (FIG. 7C, right panel). Thesefindings suggest that IL-10 producing CD1d^(high)CD5⁺ B cells functionis antigen-specific rather than a result of inflammatory stimuli.

TABLE I Spleen B lymphocyte subsets in wild type, hCD19Tg, CD19^(−/−),and IL-10^(−/−) mice^(a) B cell subset numbers (×10⁻⁵) Mouse genotypeCD1d^(high)CD5⁺ B-1a MZ Follicular hCD19Tg  18 ± 2* 32 ± 4 16 ± 1**  68± 4* Wild type  13 ± 1 30 ± 3 42 ± 3 362 ± 42 IL-10^(−/−)  12 ± 1 31 ± 242 ± 1 324 ± 17 CD19^(−/−) 0.4 ± 0.1**  8 ± 1** 12 ± 1** 148 ± 6* ^(a)Bcell subsets were: CD1d^(high)CD5⁺, B-1a (CD5⁺B220^(low)), MZ(CD1d^(high)CD21^(high)B220^(high)), and follicular(CD21^(int)CD23⁺B220^(high)). ^(b)Values (±SEM, n ≧ 4 mice) weresignificantly different from those of wild type mice, *p < 0.05, **p <0.01.

6.3 Discussion

This study demonstrates that a phenotypically distinctCD1d^(high)CD5⁺CD19^(high) B cell subset (FIG. 5) regulates Tcell-mediated inflammatory responses through the secretion of IL-10. Forconvenience, splenic IL-10-producing CD1d^(high)CD5⁺ B cells as “B10cells” are designated. These rare IL-10-producing B cells representedonly 1-2% of spleen B220⁺ cells and 7-8% of peritoneal B cells in wildtype mice, but were not normally detectable in blood or lymph nodes(FIG. 3). However, IL-10-producing CD1d^(high)CD5⁺ B cells were expandedsignificantly in the spleen (˜10% of B220⁺ cells) and peritoneal cavity(−25%) but not blood or lymph nodes of hCD19Tg mice, and was collapsedin CD19^(−/−) mice (FIGS. 3 and 5C, Table I). In parallel, the abilitiesof B cells from hCD19Tg, wild type, and CD19^(−/−) mice to modify CHSresponses (FIGS. 1 and 3) inversely paralleled their capacity to secreteIL-10 (FIGS. 2 and 3). Similarly, B cell depletion increased CHSresponses in wild type mice to the levels observed in CD19^(−/−) mice,and normalized CHS responses in hCD19Tg mice (FIG. 1). B cell depletionin CD19^(−/−) mice did not reduce CHS severity excluding the possibilitythat CD19^(−/−) B cells abnormally produce pro-inflammatory mediatorsduring CHS responses (FIG. 1D). Spleen and blood B cell IL-10 expressionwas also enhanced in wild type and hCD19Tg mice during CHS responses,but not in CD19^(−/−) mice (FIGS. 6A and E). Furthermore, blocking IL-10receptor function normalized CHS responses in hCD19Tg mice (FIG. 6C).The adoptive transfer of spleen CD1d^(high)CD5⁺ B cells from wild typeand CD20^(−/−) mice normalized CHS responses in CD19^(−/−) mice and CD20mAb-treated mice, respectively, while spleen CD1d^(high)CD5⁺ B cellsfrom IL-10^(−/−) mice were without effect (FIG. 7A-B). Thus,CD1d^(high)CD5⁺ B cell production of IL-10 regulated T cell-dependentCHS responses.

That B10 cells were found exclusively within the relatively rare spleenCD1d^(high)CD5⁺CD19^(high) B cell subset distinguishes the currentresults from previous studies (Mizoguchi and Bhan, 2006, J. Immunol.176:705-10), but also unifies most of the current studies regardingIL-10 production by B cells. Some spleen B cells and peritoneal CD5⁺B-1a cells are known to produce IL-10 (Brummel and Lenert, 2005, J.Immunol. 174:2429-34; Evans et al., 2007, J. Immunol. 178:7868-78;Fillatreau et al., 2002, Nat. Immunol. 3:944-50; Gray et al., 2007,Proc. Natl. Acad. Sci. USA 104:14080-5; Harris et al., 2000, Nat.Immunol. 1:475-82; Mauri et al., 2003, J. Exp. Med. 197:489-501; Spencerand Daynes, 1997, Int. Immunol. 9:745-54). Specifically, spleen B cellswith a CD21⁺CD23⁻ “MZ” phenotype can produce IL-10 in response to CpG(Brummel and Lenert, 2005, J. Immunol. 174:2429-34) or apoptotic cell(Gray et al., 2007, Proc. Natl. Acad. Sci. USA 104:14080-5) stimulation.Spleen CD1d⁺CD21⁺CD23⁺ B cells with a “T2-MZ precursor” phenotype alsoproduce IL-10 and can inhibit collagen-induced arthritis (Evans et al.,2007, J. Immunol. 178:7868-78). Spleen CD5⁺ B cells also produce IL-10following IL-12 stimulation, while CD5⁻ B cells do not (Spencer andDaynes, 1997, Int. Immunol. 9:745-54). Thus, spleen B10 cells share somephenotypic markers with both CD1d^(high)CD21^(high) MZ B cells andCD5⁺CD19^(high)B220^(low) B-1a cells. However, the frequency of spleenCD1d^(high)CD5⁺ B cells in wild type mice (2.3±0.1%) was significantlylower than the frequencies of spleen B-1a (6.2±0.3%, p<0.01) and MZ(6.9±0.4%, p<0.01) B cells. Moreover, IL-10 secretion was predominantlylocalized within the spleen CD1d^(high)CD5⁺ B cell subset in wild typemice, while other spleen B cells including B-1a and follicular B cellsdid not secrete IL-10 at significant frequencies (FIG. 5C). Sincefractionating such small B cell subsets with absolute purity remainstechnically difficult, it is possible that some IL-10 producing B cellsexist that are not CD1d^(high)CD5⁺, although these cells may alsorepresent B10 cells at different states of maturation. Alternatively, itis possible that B10 cells may represent an “activated” MZ or B-1asubset, although B10 cells did not selectively produce other cytokines(FIG. 3H). Thus, the CD1d^(high)CD5⁺CD19^(high) spleen subset ascurrently identified represents a relatively rare but functionallypotent population of IL-10-producing regulatory B cells.

IL-10 production likely explains the potent ability of B10 cells toregulate T cell-mediated inflammatory responses. The adoptive transferof only 2×10⁶ wild type CD1d^(high)CD5⁺ B cells normalized the CHSresponses of both CD19^(−/−) mice and mice depleted of B cells (FIG. 7).This is remarkable since not all CD1d^(high)CD5⁺ B cells produced IL-10following LPS stimulation (FIG. 5). Moreover, B10 cells may beantigen-specific since the adoptive transfer of CD1d^(high)CD5⁺ B cellsfrom antigen-sensitized mice into CD19^(−/−) recipients inhibited CHSresponses, while CD1d^(high)CD5⁺ B cells from unsensitized mice or frommice sensitized with a different antigen were without effect (FIG. 7A,C). It is not known whether splenic or peritoneal IL-10-producing Bcells affect immune responses centrally or this depends on B10 cellmigration into draining lymph nodes or peripheral tissues. However,IL-10 transcripts were not significantly increased in B cells from lymphnodes draining the sites of antigen challenge (FIG. 5A). Furthermore, Bcell infiltration is not observed in the challenged ears of wild typeand CD19^(−/−) mice during CHS responses (Watanabe et al., 2007, Am. JPathol. 171:560-70). Nonetheless, B10 cells entered the circulationduring CHS responses (FIG. 6E) and may thereby migrate in small numbersto local sites of inflammation. B cell depletion in tight skin mice, agenetic model for human systemic sclerosis, reduces IL-10, IL-4, IL-6,and TGF-β production in the skin, while B cell transcripts are not foundin the lesional skin (Hasegawa et al., 2006, Am. J. Pathol. 169:954-66).Similarly, B cell-deficient and CD19^(−/−) mice exhibit augmented EAEresponses (Fillatreau et al., 2002, Nat. Immunol. 3:944-50; Matsushitaet al., 2006, Am. J. Pathol. 168:812-21), although central nervoussystem B cells are rare during EAE (McGeachy et al., 2005, J. Immunol.3025-32). Thus, splenic and peritoneal IL-10-producing B cells may alterthe peripheral production of IL-10 and other cytokines by non-B cellscirculating through draining lymph nodes or peripheral tissue, therebyinfluencing systemic as well as local inflammatory responses.

Functional and lineage relationships between spleen B10, B-1a, and MZ Bcells, and peritoneal B-1a, B-1b, and peritoneal IL-10-producing B cellsare possible. However, their only common features identified thus farare shared phenotypic markers. Since B10 and B-1a cell frequencies areincreased in hCD19Tg mice (Table I), while B10 and B-1a cells are rarein CD19^(−/−) mice (Haas et al., 2005, Immunity 23:7-18; Sato et al.,1996, J. Immunol. 157:4371-8), it is possible that B10 cells and B-1acells represent different branches of a common lineage. By contrast,B-1b cell frequencies are increased in CD19^(−/−) mice (Haas et al.,2005, Immunity 23:7-18), while B10 cells were significantly reduced(Table I). Phenotypically- and histologically-defined MZ B cells arealso reduced in CD19^(−/−) mice, while organized marginal zones areequally difficult to identify in hCD19Tg mice by immunohistochemistrystaining (Haas et al., 2005, Immunity 23:7-18). Likewise, spleen B cellswith a CD1d^(high)CD21^(high)B220⁺ “MZ phenotype” were reduced inhCD19Tg mice, while CD1d^(high)CD5⁺ B cells numbers were increasedrelative to wild type mice (Table I). Moreover, only ˜50% of B10 cellsexhibited the CD21^(high) phenotype of MZ B cells. Nonetheless,increased numbers of splenic IL-10-producing B cells and an expandedpopulation of “MZ-like” CD1d^(high) B cells that express CD5 have beenidentified in mouse lupus models (Duan et al., 2007, Lab. Invest.87:14-28). Thus, B10 cells might be important in regulating autoimmunedisease since hCD19Tg mice develop autoimmunity with age (Sato et al.,1996, J. Immunol. 157:4371-8). Notably, IL-10 production was notrequired for CD1d^(high)CD5⁺ B cell generation since this subset waspresent in IL-10^(−/−) mice (FIG. 5C, Table I). Regardless, it isexciting to speculate that each B cell subset has different functions,with B10 cells producing IL-10 and thereby regulating T cell function,while B-1a cells produce natural and autoantibodies, B-1b cells produceadaptive immune responses to T cell-independent antigens (Haas et al.,2005, Immunity 23:7-18), and MZ B cells provide protection early duringpathogen challenge (Martin et al., 2001, Immunity 14:617-29).

That B10 cells represent a unique subset with regulatory functions invivo provides new insight into potential regulatory roles for B cellsduring immune responses and autoimmune disease. B cell depletion in miceresulted in significantly enhanced CHS responses, suggesting that B10cells regulate T cell responses (FIG. 1). B cell depletion alsosignificantly delays the onset of collagen-induced arthritis in DBA/1Jmice (Yanaba et al., 2007, J. Immunol. 179:1369-80), skin sclerosis intight skin mice (a model of systemic sclerosis) (Hasegawa et al., 2006,Am. J. Pathol. 169:954-66), Sjogren's-like disease in Id3-deficient mice(Hayakawa et al., 2007, Immunology 122:73-9), and diabetes in nonobesediabetic mice (Xiu et al., 2008, J. Immunol. 180:2863-75). By contrast,we have found that B cell depletion early in the course of diseaseworsens EAE, whereas B cell depletion at the height of diseaseameliorates EAE. This suggests the dominance of different B cellfunctions during disease progression, which may involve B10 cells.Similarly, B cell depletion in humans using a chimeric anti-human CD20mAb, was recently found to exacerbate ulcerative colitis (Goetz et al.,2007, Inflamm. Bowel Dis. 13:1365-8) and may contribute to thedevelopment of psoriasis (Dass et al., 2007, Arthritis Rheum.56:2715-8). By contrast, B cell depletion using a chimeric anti-humanCD20 mAb may benefit rheumatoid arthritis, systemic lupus erythematosus,idiopathic thrombocytopenic purpura, and pemphigus vulgaris patients(Edwards and Cambridge, 2006, Nat. Rev. Immunol. 6:394-403; El Tal etal., 2006, J. Am. Acad. Dermatol. 55:449-59). Thereby, the benefit of Bcell depletion therapy is likely to vary according to disease and therelative involvement of different B and T cell subsets. Thus, the B10cell subset that is included in a phenotypically defined CD1d^(high)CD5⁺B cell population may represent relatively rare but functionally potentregulatory cells. Regardless, further defining the role of B10 cells andother B cell subsets in disease and regulatory function in vivo mayprovide new insights and therapeutic approaches for treatinginflammatory and organ-specific autoimmunity in addition to otherdiseases.

7. EXAMPLE 2 A Role for CD1d^(HIGH)CD5⁺ Regulatory B Cells inExperimental Autoimmune Encephalomyelitis (EAE)

EAE is a T lymphocyte-mediated autoimmune disease of the CNS that modelshuman multiple sclerosis. This example shows that B lymphocytessignificantly influence EAE disease initiation and progression usingmice depleted of mature B cells but with otherwise intact immunesystems. Unexpectedly, B cell depletion before EAE inductionsignificantly exacerbated disease symptoms and increasedencephalitogenic T cell influx into the CNS. This resulted from thedepletion of a rare splenic IL-10-producing CD1d^(high)CD5⁺ regulatory Bcell subset since the adoptive transfer of these cells normalized EAE inB cell-deficient mice. By contrast, B cells were also required forCNS-autoantigen specific-CD4⁺ T cell generation during EAE development.Thereby, B cell depletion during EAE progression dramatically suppresseddisease symptoms, impaired CNS-autoantigen specific-CD4⁺ T cellexpansion, and reduced encephalitogenic T cell entry into the CNS. Theseresults demonstrate reciprocal regulatory roles for B cells during EAEimmunopathogenesis.

7.1 Materials and Methods

7.1.1 Cell Preparation and Immunofluorescence Analysis

Single-cell leukocyte suspensions from spleens, peripheral lymph nodes(paired axillary and inguinal), and bone marrow (bilateral femurs) weregenerated by gentle dissection. Mononuclear cells from the CNS wereisolated after cardiac perfusion with PBS, as described (Zeine andOwens, 1992, J. Neuroimmunol. 40:57-69). Briefly, CNS tissues weredigested with collagenase D (2.5 mg/ml, Roche Diagnostics, Mannheim,Germany) and DNaseI (1 mg/ml, Roche Diagnostics) at 37° C. for 45 min.Mononuclear cells were isolated by passing the tissue through 70-μm cellstrainers (BD Biosciences, San Diego, Calif.), followed by percollgradient (70%/37%) centrifugation. Lymphocytes were collected from the37:70% interface and washed.

Mouse CD20-specific mAb MB20-11 was used as described (Uchida et al.,2004, J. Exp. Med. 199:1659-69). FITC-, PE- or PE-Cy5-conjugated CD1d(1B1), CD3 (17A2), CD4 (H129.19), CD5 (53-7.3), CD8 (53-6.7), CD19(1D3), CD25 (PC61), CD44 (IM7), B220 (H1.2F3), Thy1.2 (53-2.1), and Tcell antigen receptor Vβ11-specific (RR3-15) mAbs were from BDBiosciences (San Diego, Calif.); anti-IgM mAb (11/41) was fromeBioscience (San Diego, Calif.). FITC-conjugated mAb reactive withL-selectin (CD62L; clone LAM1-116) was as described (Steeber et al.,1997, J. Immunol. 159:952-63). Intracellular staining used mAbs reactivewith IFN-γ (XMG1.2), IL-17A (eBiol7B7), and Foxp3 (FJK-16s) (all fromeBioscience) and the Cytofix/Cytoperm kit (BD Biosciences). Forintracellular cytokine staining, lymphocytes were stimulated in vitrowith phorbol 12-myristate 13-acetate (10 ng/ml; Sigma, St. Louis, Mo.)and ionomycin (1 μg/ml; Sigma), in the presence of monensin (1 μl/ml;eBioscience) for 4 hours before staining. MOG₃₈₋₄₉IAb tetramer andcontrol tetramer (CLIP/IAb) were constructed and supplied by the NIHTetramer Core Facility (Atlanta, Ga.). Background staining was assessedusing non-reactive, isotype-matched control mAbs (Caltag Laboratories,San Francisco, Calif.). For two- or three-color immunofluorescenceanalysis, single cell suspensions (10⁶ cells) were stained at 4° C.using predetermined optimal concentrations of mAb for 20 minutes asdescribed (Zhou et al., 1994, Mol. Cell. Biol. 14:3884-94). For tetramerstaining, lymphocytes were stained for 3 hours at 37° C. as described(Falta et al., 2005, Arth. Rheum. 52:1885-96). Blood erythrocytes werelysed after staining using FACS™ Lysing Solution (Becton Dickinson, SanJose, Calif.). Cells with the forward and side light scatter propertiesof lymphocytes were analyzed using a FACScan flow cytometer (BectonDickinson).

7.1.2 Mice

Female C57BL/6 (B6) mice were obtained from The Jackson Laboratory (BarHarbor, Me.). CD20^(−/−) mice were as described (Uchida et al., 2004,Int. Immunol. 16:119-29). TCR^(MOG) transgenic mice whose CD4⁺ T cellsrespond to MOG₃₅₋₅₅ peptide (Bettelli et al., 2003, J. Exp. Med.197:1073-81) were provided by Dr. V. K. Kuchroo (Harvard Medical School,Boston, Mass.). Mice were housed in a specific pathogen-free barrierfacility.

7.1.3 EAE Induction and Immunotherapy

Active EAE was induced in female B6 (six- to eight-week-old) mice bysubcutaneous immunization with 100 μg of MOG₃₅₋₅₅ peptide(MEVGWYRSPFSRVVHLYRNGK; NeoMPS, San Diego, Calif.) emulsified in CFAcontaining 1 mg/ml of heat-killed Mycobacterium tuberculosis H37RA(Sigma-Aldrich, St. Louis, Mo.) on day 0. Additionally, mice received200 ng of pertussis toxin (List Biological Laboratories, Campbell,Calif.) intraperitoneally in 0.5 ml of PBS on days 0 and 2. Clinicalsigns of EAE were assessed daily with a 0-6 scoring system (0, no signs;1, flaccid tail; 2, impaired righting reflex and/or gait; 3, partialhind limb paralysis; 4, total hind limb paralysis; 5, hind limbparalysis with partial fore limb paralysis; 6, moribund state)(Fillatreau et al., 2002, Nat. Immunol. 3:944-50). To deplete B cells invivo, sterile CD20 (MB20-11, IgG2c) or isotype-matched control mAbs (250μg) were injected in 200 μl PBS through lateral tail veins (Uchida etal., 2004, Int. Immunol. 16:119-29).

7.1.4 Histology

Following an initial perfusion with PBS, animals were perfusedtranscardially with 4% paraformaldehyde and spinal cords were removed.Tissues were processed and blocked in paraffin wax. Transverse spinalcord sections were stained with H&E for assessment of inflammation andwith Luxol Fast Blue for demyelination. Sections were assessed asfollows: inflammation: 0, none; 1, a few inflammatory cells; 2,organization of perivascular infiltrates; and 3, increasing severity ofperivascular cuffing with extension into adjacent tissues. Fordemyelination: 0, none; 1, rare foci; 2, a few areas of demyelination;3, large (confluent) areas of demyelination (Calida et al., 2001, J.Immunol. 166:723-6).

7.1.5 Serological Evaluation of MOG Peptide-Specific Ab Production

To evaluate MOG peptide-specific Ab production, 96 well microtiterplates (Costar, Cambridge, Mass.) were coated with 10 μg/ml of MOGpeptide. Plates were incubated with serum samples diluted 1:100, withbound antibody detected using alkaline phosphatase-conjugated goatanti-mouse IgG or IgM Abs (Southern Biotechnology Associates, Inc.,Birmingham, Ala.).

7.1.6 Adoptive Transfer Experiments

CD4⁺ T cells were isolated from pooled spleens and lymph nodes ofTCR^(MOG) transgenic mice using an isolation kit from Miltenyi Biotech(Auburn, Calif.). TCR^(MOG) CD4⁺ T cells were then labeled with CFSEVybrant™ CFDA SE fluorescent dye (5 μM; CFSE; Invitrogen-MolecularProbes, Carlsbad, Calif.) as described (Quah et al., 2007, Nat. Protoc.2:2049-56). Labeled TCR^(MOG) CD4⁺ T cells (5×10⁶) were then transferredi.v. into mice. Four days after adoptive transfer, T cells were stainedfor CD4 and Vβ11 expression with proliferation assessed by flowcytometry.

Splenic B cells were purified from CD20^(−/−) mice using CD19mAb-coupled microbeads (Miltenyi Biotech). In addition, CD1d^(high)CD5⁺B cells were isolated using a FACSVantage SE flow cytometer (BectonDickinson) with purities of 95-98%. After isolation, 2×10⁶CD1d^(high)CD5⁺ or non-CD1d^(high)CD5⁺ B cells were immediatelytransferred i.v. into B cell-depleted recipient mice 2 days before EAEinduction.

7.1.7 Statistical Analysis

All data are shown as means±SEM. The significance of differences betweensample means was determined using the Student's t test.

7.2 Results

7.2.1 B Cells are Capable of Inhibiting and Augmenting EAE

To assess the contributions of B cells during EAE induction orprogression, mice were given CD20 mAb either 7 days before EAE induction(day -7) or when EAE symptoms were present on day 14. The CD20-specificmAb was mouse antibody MB20-11 and was used as described (Uchida et al.,2004, J. Exp. Med. 199:1659-69). In both cases, CD20 mAb significantlydepleted the majority of mature B cells in the bone marrow, blood,spleen, and peripheral lymph nodes by day 18 after EAE induction, whilecontrol mAb treatment was without effect (FIG. 8 and Table II).Peritoneal cavity B cells are more resistant to CD20 mAb-mediateddepletion (Hamaguchi et al., 2005, J. Immunol. 4389-99), which explainstheir less complete depletion 4 days after day 14 CD20 mAb injection.Nonetheless, MOG immunization did not significantly affect B cell subsetdepletion when compared with unimmunized mice (Yanaba et al., 2007, J.Immunol. 179:1369-80; DiLillo et al., 2008, J. Immunol. 180:361-71).

In mice treated with CD20 or control mAb, EAE symptoms first appearedaround day 12 with similar disease incidence (93-100%, FIG. 9A and TableIII). However, mice depleted of B cells before MOG immunizationexhibited significantly worse disease. This included a more severe peakin disease syMptom severity and disease persisting longer when comparedwith control mAb-treated mice (p<0.05, FIG. 9A left panel and TableIII). By contrast, B cell depletion during EAE development dramaticallyreduced disease severity at all time points when compared with controlmAb-treated mice (p<0.05, FIG. 9A right panel and Table III).Microscopic examination of CNS tissues collected from each group of miceon day 18 revealed that B cell depletion before EAE induction resultedin more robust leukocyte infiltration into the CNS and more significantdemyelination when compared with control mAb-treated mice (p<0.05, FIG.9B). B cell depletion during EAE development resulted in reducedleukocyte infiltration and significantly less demyelination whencompared with control mAb-treated mice (p<0.05). Thus, the presence of Bcells had profound effects on disease course and CNS leukocyteinfiltration that was dependent on whether B cells were depleted beforedisease induction or after symptoms developed.

TABLE II Tissue B cell depletion following EAE induction and CD20 mAbtreatment^(a) Treated day −7^(c) Treated day (% Depletion) 14 (%Depletion) Tissue B subset^(b) Control mAb CD20 mAb Control mAb CD20 mAbBone marrow: Pro/pre 0.10 ± 0.04 0.11 ± 0.05 (0) 0.09 ± 0.03 0.09 ± 0.05(0) Immature 0.16 ± 0.10 0.04 ± 0.02 (72) 0.16 ± 0.04 0.04 ± 0.02 (72)Mature 0.48 ± 0.16 0.01 ± 0.01 (99*) 0.51 ± 0.14 0.01 ± 0.01 (97*)Blood: B220⁺ 3.2 ± 0.9 0.03 ± 0.01 (99*) 3.0 ± 0.7 0.05 ± 0.02 (98*)Spleen: B220⁺ 20.0 ± 6.5  0.07 ± 0.02 (99*) 19.6 ± 1.3   1.8 ± 0.6 (91*)Mature 11.4 ± 4.3  0.02 ± 0.02 (99**) 12.6 ± 1.3  0.68 ± 0.31 (95*) T11.5 ± 0.6 0.02 ± 0.02 (99*) 1.4 ± 0.5 0.18 ± 0.07 (87*) T2 1.2 ± 0.50.01 ± 0.01 (99*) 1.3 ± 0.4 0.01 ± 0.01 (99*) Marginal zone 1.9 ± 0.70.01 ± 0.02 (99*) 1.9 ± 0.4 0.01 ± 0.01 (99*) Peripheral LN: B220⁺ 1.2 ±0.4 0.05 ± 0.02 (95*) 1.2 ± 0.3 0.43 ± 0.08 (65*) Peritoneum: B220⁺ 1.2± 0.2 0.01 ± 0.01 (99**) 1.3 ± 0.1 0.14 ± 0.08 (89*) B1a 0.11 ± 0.030.01 ± 0.01 (95*) 0.13 ± 0.03 0.05 ± 0.01 (62) B1b 0.12 ± 0.04 0.01 ±0.01 (95*) 0.12 ± 0.01 0.05 ± 0.02 (63) B2 1.0 ± 0.4 0.01 ± 0.01 (99*)1.14 ± 0.37 0.13 ± 0.08 (90*) ^(a)Mice were treated with mAb (250 μg) 7days before or 14 days after MOG immunization. Tissue B cell numberswere determined on day 18 (n ≧ 4 mice per value). ^(b)B cell subsetswere: bone marrow pro/pre (IgM⁻B220^(low)), immature (IgM⁺B220^(low)),mature (IgM⁺B220^(high)); spleen mature (CD24⁺CD21⁺B220⁺), T1(CD24^(high)CD21⁻B220⁺), T2 (CD24^(high)CD21⁺B220⁺), and marginal zone(CD21^(high)CD1d⁺B220⁺); peritoneal B-1a(CD5⁺CD11b⁺IgM^(high)B220^(low)), B-1b (CD5⁻CD11b⁺IgM^(high)B220^(low))and B2 (CD5⁻IgM^(low)B220^(high)). LN, lymph node. ^(c)Values (±SEM)indicate cell numbers (×10⁻⁶) present in each tissue. Blood results areshown as cells/ml. Significant differences between CD20 versus controlmAb-treated mice are indicated; *p < 0.05, **p < 0.01.

TABLE III EAE clinical scores following CD20 mAb treatment^(a) Mean dayMean maximum Group Incidence^(c) of onset score Untreated^(b)  9/10(90%) 13.1 ± 0.5 2.6 ± 0.8 Day −7 control mAb 13/14 (93%) 13.0 ± 0.5 2.8± 0.6 Day −7 CD20 mAb 14/14 (100%) 12.9 ± 0.5 4.3 ± 0.4** Day 14 controlmAb 14/15 (93%) 12.9 ± 0.4 2.9 ± 0.7 Day 14 CD20 mAb 14/15 (93%) 12.9 ±0.3 1.5 ± 0.4* ^(a)Mice were treated with CD20 or control mAb (250 μg) 7days before or 14 days after MOG immunization. ^(b)The untreated groupwas not treated with mAb. ^(c)Assessment of clinical EAE includes thenumber of mice that developed disease, the mean day of disease onset ±SEM among mice with EAE, and the mean maximum clinical score ± SEM ofeach treatment group. The mean maximum clinical score was obtained forthe group over the entire observation period. Significant differencesbetween CD20 versus control mAb-treated mice are indicated; *p < 0.005,**p < 0.0005.

7.2.2 Depletion of B Cells Abrogates Mog-Specific Antibody Production

The effect of B cell depletion on serum antibody responses was assessedsince MOG-specific antibodies enhance CNS demyelination andinflammation, and increase EAE severity (Linington et al., 1988, Am. J.Pathol. 130:443-54; Lyons et al., 1999, Eur. J. Immunol. 29:3432-9).Control mAb-treated mice produced significant IgM and IgG MOG-specificantibody responses by day 18 after immunization when compared withunimmunized littermates (FIG. 9C, p<0.001). MOG-specific IgG antibodylevels increased in parallel with disease progression, whileMOG-specific IgM antibody levels decreased significantly after day 18(p<0.05). B cell depletion before MOG immunization completely abrogatedMOG-specific IgM and IgG antibody production. B cell depletion afterdisease initiation significantly inhibited both MOG-specific IgM and IgGantibody production at the peak of disease (p<0.001 and p<0.01,respectively) and IgG production during the recovery phase (p<0.01),consistent with results obtained using other immunogens (DiLillo et al.,2008, J. Immunol. 180:361-71). Thus, B cell depletion before EAEinduction and during EAE development significantly attenuatedautoantibody production, which did not correlate with increased EAEseverity following early B cell depletion.

7.2.3 Depletion of B Cells During Eae Development ReducesAntigen-Specific T Cell Proliferation

B cells are important for encephalitogenic T cell activation (Bettelliet al., 2006, J. Clin. Invest. 116:2393-402; Krishnamoorthy et al.,2006, J. Clin. Invest. 116:2385-92) and for antigen-specific T cellproliferation in diabetes and arthritis models (Bouaziz et al., 2007,Proc. Natl. Acad. Sci. USA 20882-7; Xiu et al. 2008, J. Immunol.180:2863-75). Therefore, the effects of B cell depletion onantigen-specific T cell proliferation in EAE mice was assessed by theadoptive transfer of CFSE-labeled CD4⁺ T cells from TCR^(MOG) mice(Bettelli et al., 2003, J. Exp. Med. 197:1073-81) on day 17. Four daysafter adoptive transfer, CFSE dilution as a marker for cell division wasassessed by flow cytometry. The frequencies and numbers of dividingTCR^(MOG) CD4⁺ T cells within lymph nodes were comparable between micetreated with CD20 or control mAb before EAE induction (FIG. 10A).However, B cell depletion during EAE development significantly inhibitedTCR^(MOG) T cell proliferation (p<0.001, FIG. 10A). Therefore, B celldepletion during EAE development but not before EAE induction,significantly reduced MOG-specific CD4⁺ T cell expansion in vivo.

Following B cell depletion on days −7 or 14, spleen CD4⁺ and CD8⁺ T cellnumbers were not changed 18 days after EAE induction (FIG. 10B and TableIV). Numbers of naïve CD44⁻CD62L⁺, activated CD44⁺CD62L⁺, memoryCD44⁺CD62L⁻, and regulatory CD25⁺FoxP3⁺ (T-reg) CD4⁺ T cells were notchanged following CD20 mAb treatment either before and after EAEinduction (FIGS. 10B-C and Table IV). Likewise, CD20 mAb treatmenteither before EAE induction or during EAE development did not affectlymph node T cell numbers, subsets, or phenotypes when compared withcontrol mAb-treated littermates. Thus, B cell depletion did not haveglobal effects on T cell numbers or phenotypes, but appeared toselectively affect antigen-specific T cell expansion late in the courseof disease.

TABLE IV Spleem T cell population following EAE induction and CD20 mAbtreatment^(a) Treated day −7^(b) Treated day 14 T subset Control mAbCD20 mAb Control mAb CD20 mAb CD4⁺CD3⁺ 5.6 ± 0.3 5.3 ± 0.8 5.0 ± 0.7 5.4± 0.8 CD8⁺CD3⁺ 5.4 ± 0.3 5.9 ± 0.8 5.4 ± 0.8 4.8 ± 0.6 CD44⁻CD62L⁺CD4⁺2.2 ± 0.1 2.9 ± 0.3 2.1 ± 0.1 2.5 ± 0.3 CD44⁺CD62L⁺CD4⁺ 0.46 ± 0.07 0.39± 0.09 0.43 ± 0.06 0.38 ± 0.05 CD44⁺CD62L⁻CD4⁺ 1.3 ± 0.2 0.9 ± 0.2 1.3 ±0.2 1.2 ± 0.2 CD25⁺FoxP3⁺CD4⁺ 0.48 ± 0.12 0.33 ± 0.08 0.47 ± 0.22 0.50 ±0.24 ^(a)Mice were treated with mAb (250 μg) 7 days before or 14 daysafter MOG immunization, both T cell numbers determined on day 18 (n ≧ 4mice per value). ^(b)Values (±SEM) indicate cell numbers (×10⁻⁶).

7.2.4 B cell depletion modifies encephalitogenic T cells within the CNS

To assess whether CNS-infiltrating T cells are affected by B celldepletion, the frequencies of MOG-specific T-effector and T-reg cellswere quantified on day 18 using MOG₃₈₋₄₉/IAb tetramers. MOG-specific Tcells preferentially accumulated within the CNS, but were only detectedat very low frequencies in spleen and lymph nodes (FIG. 11A). B celldepletion before EAE induction resulted in significantly expandedMOG-specific T-effector cell numbers in the CNS when compared withcontrol mAb-treated littermates (p<0.05). The number of MOG-specificT-reg cells in B cell-depleted mice was not changed, which resulted in asignificantly higher ratio of T-effector/T-reg cells (p<0.01).Conversely, MOG-specific T-effector and T-reg cell numbers within theCNS were significantly reduced in mice depleted of B cells during EAEdevelopment (p<0.05).

Since IFN-γ and IL-17 play critical roles in EAE development (Kuchroo etal., 1993, J. Immunol. 151:4371-82; Baron et al., 1993, J. Exp. Med.177:57-68; Park et al., 2005, Nat. Immunol. 6:1133-41; Bettelli et al.,2006, Nature 235-8), their expression by CNS-infiltrating CD4⁺ T cellswas assessed 18 days after MOG immunization. B cell depletion before EAEinduction significantly increased the numbers of IFN-γ and IL-17producing CD4⁺ T cells within the CNS as analyzed by intracellularcytokine staining (p<0.05, FIG. 11B). Conversely, B cell depletionduring EAE development resulted in significantly reduced numbers ofIFN-γ and IL-17 producing CD4⁺ T cells (p<0.05). Thus, B cell depletionbefore EAE induction increased encephalitogenic CD4⁺ T cell expansionwithin the CNS, whereas B cell depletion during EAE development reducedthe influx of encephalitogenic CD4⁺ T cells.

7.2.5 CD1d^(high)CD5⁺ Regulatory B Cells Inhibit EAE

As described in Example 1, we have identified a population of B cellsthat can inhibit T cell-mediated inflammation through IL-10 production.These regulatory IL-10-producing B cells are found within a rareCD1d^(high)CD5⁺ subset and can inhibit the induction of antigen-specificinflammatory reactions. Therefore, whether EAE exacerbation following Bcell depletion resulted from the lack of CD1d^(high)CD5⁺ regulatory Bcells was assessed through adoptive transfer experiments. SplenicCD1d^(high)CD5⁺ B cells and non-CD1d^(high)CD5⁺ B cells were purifiedfrom CD20^(−/−) mice (FIG. 12A) and transferred into wild type mice thathad been depleted of B cells using CD20 mAb before EAE induction.CD20^(−/−) B cells are resistant to CD20 mAb-mediated B cell depletion(Uchida et al., 2004, J. Exp. Med. 199:1659-69). Adoptive transfer ofonly 2×10⁶ CD1d^(high)CD5⁺ B cells completely normalized disease in Bcell-deficient mice, while total B cell depletion exacerbated EAE inwild type mice (FIG. 12B). By contrast, the adoptive transfer ofnon-CD1d^(high)CD5⁺ B cells into B cell depleted mice did not affect EAEseverity. Thus, regulatory CD1d^(high)CD5⁺ B cells play a protectiverole during EAE initiation.

7.3 Discussion

These studies show that B cells play critical positive and negativeregulatory roles in EAE immunopathogenesis. Consequently, B celldepletion had two opposing effects on disease. B cell depletion beforeEAE induction resulted in the increased influx or expansion ofencephalitogenic T cells within the CNS (FIG. 11), which significantlyexacerbated disease symptoms (FIG. 9A-B). Since the adoptive transfer ofregulatory B cells within the CD1d^(high)CD5⁺ subset, but not other Bcells, normalized EAE (FIG. 12), we propose that increased EAE severityfollowing B cell depletion results from the effective depletion of thisB cell subset (FIG. 8). Conversely, B cell depletion during EAEdevelopment impaired MOG-specific T cell expansion (FIG. 10C) andsignificantly inhibited the influx or expansion of encephalitogenic Tcells within the CNS (FIG. 11), which dramatically suppressed diseasesymptoms (FIG. 9A-B). Thereby, B cells were also essential forgenerating optimal pathogenic CD4⁺ T cell responses following MOGimmunization. The reciprocal positive and negative regulatory roles of Bcells are likely to overlap during the course of disease, with thebalance of these two opposing influences shaping the normal course ofEAE immunopathogenesis. This is likely to also occur in other Tcell-mediated autoimmune diseases.

The current findings resolve previously unexplained contradictionsbetween previous studies showing the importance of B cells in EAE.Exacerbated disease after early CD20 mAb treatment can be explained bythe depletion of IL-10-producing regulatory CD1d^(high)CD5⁺ B cells(FIGS. 8 and 12). B cells have been previously shown to suppress EAEthrough IL-10 production (Fillatreau et al., 2002, Nat. Immunol.3:944-50). IL-10-producing B cells can also down-regulate otherautoimmune and inflammatory diseases, such as collagen-inducedarthritis, inflammatory bowel disease, and contact hypersensitivity(Mauri et al., 2003, J. Exp. Med. 197:489-501; Mizoguchi et al., 2002,Immunity 16:219-30). That B cell depletion enhanced EAE severity in theabsence of MOG-specific autoantibodies (FIG. 9C) also argues that Bcells and their antibody products are not required for EAE induction.Ameliorated disease progression following B cell depletion after EAEsymptom onset (FIG. 9A) can be explained by inhibition of CD4⁺ T cellactivation (FIGS. 10, 11). That B cells may serve as antigen presentingcells to prime MOG-specific T cells (Lyons et al., 1999, Eur. J.Immunol. 29:3432-9; Bettelli et al., 2006, J. Clin. Invest.116:2393-402; Krishnamoorthy et al., 2006, J. Clin. Invest. 116:2385-92)provides a mechanistic explanation for this observation. A role for Bcells in early antigen presentation and CD4⁺ T cell activation is alsopossible, but this may be obscured by the use of a potent adjuvantduring MOG immunization. Alternatively, B cells may play a more criticalrole in antigen presentation or CD4⁺ T cell activation after diseaseinitiation with dendritic cells and other antigen presenting cells moreimportant for disease initiation. Mice genetically deficient for B cellsdevelop EAE normally but fail to resolve the disease (Wolf et al., 1996,J. Exp. Med. 184:2271-8; Fillatreau et al., 2002, Nat. Immunol.3:944-50). By contrast, early B cell depletion in mice with otherwisenormal immune systems exacerbated not only the recovery phase of EAE butalso the peak phase of EAE induction (FIG. 9A). This apparentcontradiction may reflect the observation that immune system developmentand T cell priming are abnormal in mice lacking B cells since birth(AbuAttieh et al., 2007, J. Immunol. 178:2950-60; Chiu et al., 2001,Diabetes 50:763-70). Thereby, an absence of regulatory B cells combinedwith abnormal T cell activation due to the total absence of B cells mayexplain normal EAE induction in congenitally B cell-deficient mice.Regardless, the lack of disease resolution in both models suggests thatregulatory B cells are likely to be critical for not only regulatingdisease induction but also for resolving disease.

That B cell depletion after the onset of EAE symptoms ameliorateddisease progression (FIG. 9A) makes this strategy applicable fortreating human MS after disease onset. However, adverse diseasefollowing B cell depletion before EAE induction in the current studysuggests that B cell depletion may promote the occurrence of MS symptomsin some undiagnosed cases. Nonetheless, B cell depletion during EAEdevelopment reduced EAE severity both clinically and histologically(FIG. 9A-B), and was accompanied by significantly reduced autoantibodylevels (FIG. 9C). Reduced autoantibody production may be clinicallyimportant since plasma exchange can reduce clinical disease activity ina subset of MS patients (Kieseier and Hartung, 2003, Semin Neurol.23:133-46; Weinshenker et al., 1999, Ann. Neurol. 46:878-86). However,CD20 mAb treatment does not lead to the depletion of long-lived plasmacells in mice (DiLillo et al., 2008, J. Immunol. 180:361-71) so CD20⁺ Bcell depletion may be most beneficial when carried out before thelong-lived plasma cell pool is established. Similarly, B cell depletionsignificantly attenuates early foreign- and autoantigen-specific CD4⁺ Tcell proliferation in vivo (Bouaziz et al., 2007, Proc. Natl. Acad. Sci.USA 104:20882-7). Also, B cell depletion early in the course of diabetesin NOD mice (Xiu et al., 2008, J. Immunol. 180:2863-75),collagen-induced arthritis in DBA-1 mice (Yanaba et al., 2007, J.Immunol. 179:1369-80), Sjogren's-like disease in Id3-deficient mice(Hayakawa et al., 2007, Immunology 122:73-9), and systemicsclerosis-like disease in tight skin mice (Hasegawa et al., 2006, Am. J.Pathol. 169:954-66) has maximal benefit. However, in these cases, it wasnot possible to reverse T cell expansion or disease progression onceinflammatory disease was initiated. Thereby, B cell depletion shortlyafter diagnosis may offer the most optimal strategy for diseasemanagement.

As shown in the studies described in Section 6, supra, IL-10-producingCD1d^(high)CD5⁺ B cells regulate T cell-mediated inflammatory responsesin a contact hypersensitivity model. Thereby, B cells can be dividedinto two functionally distinct subsets in autoimmunity: regulatory Bcells and B cells that can activate CD4⁺ T cells. The therapeutic effectof B cell depletion likely depends on the contributions and the timingof these B cell subsets during the course of each autoimmune disease.The current studies suggest that the selective depletion of mature Bcells while sparing IL-10-producing B cells may offer a potenttherapeutic approach. Moreover, the in vivo or in vitro expansion ofIL-10-producing regulatory B cells may also offer a new strategy fortreating patients with MS and other autoimmune or inflammatory diseases.

8. EXAMPLE 3 Identification of a Human Regulatory B Cell Population

A population of IL-10 producing human B cells was identified. Peripheralblood mononuclear cells (PBMC) were isolated from four healthy humandonors and activated in vitro in RPMI 1640 media containing 10% fetalbovine serum (FBS), 10 μg/ml of LPS, 50 ng/ml of PMA, 500 ng/ml ofionomycin, and monensin for 5 hours. IL-10⁺ and IL-10⁻ B cells wereexamined by immunofluorescence staining with flow cytometry analysisusing cytoplasmic IL-10 expression and cell surface CD19 expression asmarkers for identifying the cells. A population of CD19⁺ B cells thatproduce IL-10 was identified in each of the four subjects (FIG. 14).These IL-10 producing B cells represented between 0.25 and 0.63 percentof the overall B cell population across the four donors and likelyrepresent the human regulatory B cell counterpart to the regulatory Bcell subset identified in mice, as described above.

9. EXAMPLE 4 Expansion of the IL-10 Producing B Cell Population by CD40Ligation

Human and murine B cell IL-10 production was measured followingstimulation with anti-CD40 mAb. Peripheral blood mononuclear cells frommice and healthy human volunteers were isolated from heparinized bloodafter centrifugation over a discontinuous Lymphoprep (Axis-Shield PoCAs, Oslo, Norway) gradient. Viable cells were counted using ahemocytometer, with relative lymphocyte percentages determined by flowcytometry analysis. Subsequently, isolated cells were resuspended (2×10⁶cells/ml) in complete medium (RPMI 1640 media containing 10% FCS, 200μg/ml penicillin, 200 U/ml streptomycin, 4 mM L-Glutamine, and 5×10⁻⁵ M2-mercaptoethanol; all from Gibco, Carlsbad, Calif.) with LPS (10 μg/ml,Escherichia coli serotype 0111: B4, Sigma), PMA (50 ng/ml; Sigma),ionomycin (500 ng/ml; Sigma), and monensin (2 μM; eBioscience, SanDiego, Calif.) for 5 h, in 24-well flat-bottom plates. In some cases,the cells were cultured with anti-human CD40 mAb for 48 hours with PMA,ionomycin, and monensin added during the final for 5 hours of culture.

Single cell suspensions of cultured cells were incubated with anti-mouseFc receptor mAb (2.4G2; BD PharMingen) to block Fc receptors, beforecell surface staining on ice using predetermined optimal concentrationsof each antibody. The cells were washed, fixed, and permeabilized usingthe Cytofix/Cytoperm kit (BD PharMingen) according to the manufacturer'sinstructions. For cytoplasmic IL-10 detection, permeabilized cells werestained with phycoerythrin-conjugated anti-human-IL-10 mAb (JES3-9D7,eBiosocience). Cells with the light scatter properties of lymphocyteswere analyzed by 2-4 color immunofluorescence staining with analysisusing FACScan or FACSCalibur flow cytometers (Becton Dickinson, SanJose, Calif.). Background staining was determined using unreactiveisotype-matched control mAbs (Caltag Laboratories, San Francisco,Calif.) with gates positioned to exclude ≧98% of unreactive cells:

Anti-human CD40 mAb stimulation of blood B cells from healthy humanvolunteers for 48 hours with LPS, PMA and ionomycin stimulation duringthe last 5 hours of culture induced significantly higher levels ofIL-10-producing B cells (0.7±0.2% p<0.05), when compared with blood Bcells cultured with LPS, PMA, and ionomycin stimulation alone for 5hours (FIG. 13). Parallel results with circulating mouse cells are shownas controls. Therefore, human blood contains IL-10 competent B cells,with prolonged CD40 stimulation enhancing the numbers of circulatinghuman blood B cells that can be induced to express cytoplasmic IL-10.

10. EXAMPLE 5 Determination of a Role for regulatory B Cells in Cancer

To understand the role that B cells play in tumor-specific immuneresponses, we have adapted and developed an in vivo murine, tumor modelto understand whether B cells play a significant role in the immunesystem's natural defenses against tumor growth. We utilized a primarycutaneous melanoma model in which mice were injected subcutaneously withB16 melanoma tumor cells one week after treatment with either CD20 orcontrol mAb. Tumor growth was measured in terms of tumor volume on days7 and 14 after tumor injection. Remarkably, tumor growth wassignificantly enhanced in B cell-depleted mice, as their tumors wereapproximately twice the volume of tumors from control mice (FIG. 15). Wehave also exploited a lung metastasis melanoma tumor model. Mice weretreated with either control or CD20 mAb seven days before intravenousadministration of B16 melanoma cells. As in the primary cutaneous tumormodel, tumor growth and metastasis was significantly enhanced in Bcell-depleted mice. These mice contained approximately twice the numberof metastasis spots on their lungs, and the sizes of these spots wereincreased compared to control mice (FIG. 15). The augmented growth oftumors in B cell-depleted mice is likely due to impaired CD4⁺ and CD8⁺ Tcell activation in the absence of B cells. Therefore, B cells arerequired for the host to mount a normal immune response to melanoma.

In addition, we have developed a new mouse lymphoma model using primaryCD20⁺ tumor cells from a C57BL/6 Eμ-cMyc transgenic mouse. CD20 mAbtreatment of syngeneic mice with adoptively transferred lymphomasprevents tumor development or significantly prolongs mouse survivaldepending on tumor volume, mAb dose, and treatment timing. By contrast,when CD20^(−/−) mice that are resistant to B cell depletion with CD20mAbs were implanted with these CD20 mAb-susceptible CD20⁺ lymphomacells, there was no difference in survival between mice receivingcontrol or CD20 mAbs (FIG. 16). This indicates that the host immunesystem's ability to control tumor cell growth is impaired when B cellsare present. Thereby, when host B cells are ablated, anti-tumor immunityis enhanced. Therefore, these data suggest an important role forregulatory B cells in lymphoma tumor immunity.

The results observed in EAE, contact hypersensitivity, and lymphomamouse models indicate that IL-10-producing B10 cells play a significantnegative role in the regulation of immune responses. Thus, it is likelythat regulatory B cells can impair a host's ability to mount maximallyeffective natural and vaccine-induced anti-tumor immune responses.Further, the specific depletion of B10 cells may enhance both naturaland vaccine-induced anti-tumor immune responses, thereby leading toincreased tumor rejection and prolonged host survival.

11. EXAMPLE 6 The Development and Function of CD1d^(HIGH)CD5⁺ RegulatoryB Cells (B10 Cells) Requires Antigen Receptor Diversity and TLR Signals

Autoimmunity and inflammation are controlled in part by regulatory Bcells, including a recently identified IL-10-competent CD1d^(hi)CD5⁺ Bcell subset termed B10 cells that represents 1-3% of adult mouse spleenB cells. In this study, pathways that influence B10 cell generation andIL-10 production were identified and compared with previously describedregulatory B cells. IL-10-competent B cells were predominantlyCD1d^(hi)CD5⁺ in adult spleen and were the prevalent source of IL-10 butnot other cytokines. B10 cell development and/or maturation in vivorequired Ag receptor diversity and intact signaling pathways, but not Tcells, gut-associated flora, or environmental pathogens. Spleen B10 cellfrequencies were significantly expanded in aged mice and micepredisposed to autoimmunity, but were significantly decreased in mousestrains that are susceptible to exogenous autoantigen-inducedautoimmunity. LPS, PMA, plus ionomycin stimulation in vitro for 5 hoursinduced B10 cells to express cytoplasmic IL-10. However, prolonged LPSor CD40 stimulation (48 h) induced additional adult spleen CD1d^(hi)CD5⁺B cells to express IL-10 following PMA+ionomycin stimulation. ProlongedLPS or CD40 stimulation of newborn spleen and adult blood or lymph nodeCD1d^(lo) and/or CD5⁻ B cells also induced cytoplasmic IL-10 competencein rare B cells, with CD40 ligation uniformly inducing CD5 expression.IL-10 secretion was induced by LPS signaling through MyD88-dependentpathways, but not following CD40 ligation. LPS stimulation also inducedrapid B10 cell clonal expansion when compared with other spleen B cells.Thereby, both adaptive and innate signals regulate B10 cell development,maturation, CD5 expression, and competence for IL-10 production.

11.1 Materials and Methods

11.1.1 Mice

Wild type C57BL/6 (B6), IL-10^(−/−) (B6.129P2-Il10^(tmlCgn)/J), NOD(NOD/Lt), DBA/1J, SJL/J, NZB/W F1 (NZBWF1/J), CD40^(−/−)(B6.129P2-CD40^(tmlKik)/J), MRL/lpr (MRL/MpJ-Fas^(lpr)/J), MD4(C57BL/6-Tg(TghelMD4)4 Ccg/J) that express IgM and IgD specific for HEL(Goodnow, et al. 1988. A Nature 334:676-682), and nude(C57BL/6-Hfhll^(nu)) mice were from the Jackson Laboratory (Bar Harbor,Me.). MHC-I/II^(−/−) (B6.129-H2-Ab1^(tmlGru)B2 m^(tmJae)N17 from TaconicFarms, Inc., Hudson, N.Y.) mice were as described (Grusby, et al. 1993.Proc. Natl. Acad. Sci. USA 90:3913-3917) and were provided by Y. Zhuang(Duke University, Durham, N.C.). MyD88^(−/−) mice (Adachi, et al. 1998.Immunity 9:143-150) were provided by Y. Yang (Duke University) with thepermission of S. Akira (Osaka University, Osaka Japan). CD22^(−/−),CD21^(−/−), CD19^(−/−) and hCD19Tg (h19-1 line) mice on a B6 geneticbackground were as described (Poe, et al. 2004. Nat. Immunol.5:1078-1087; Sato, et al. 1996. J. Immunol. 157:4371-4378; Sato, et al.1997. J. Immunol. 158:4662-4669; Haas, et alr. 2002. Immunity17:713-723). CD40L/BTg mice with B cells expressing cell surface CD40Lwere as described (Higuchi, et al. 2002. J. Immunol. 168:9-12).CD40LIBTg/CD22^(−/−) double mutant mice were generated by crossingCD40L/BTg mice with CD22^(−/−) mice. B6 neonates were 3 to 10 days old.All mice were housed in a specific pathogen-free barrier facility andused at 12-16 wk of age, unless otherwise specified. All studies wereapproved by the Duke University Animal Care and Use Committee. Tissuesfrom 6 mo-old gnotobiotic and specific-pathogen-free 129S6/SvEv micewere generously provided by Dr. Scott Plevy and the Univ. of NorthCarolina at Chapel Hill Center for Gastrointestinal Biology & DiseaseGnotobiotic Core.

11.1.2 Antibodies

Anti-mouse mAbs included: B220 mAb RA3-6B2 (provided by Dr. RobertCoffman, DNAX Corp., Palo, Alto, Calif.); and CD19 (1D3), CD5 (53-7.3),CD1d (1B1), CD40 (HM40-3), CD21/35 (7G6), CD23 (B3B4), CD24 (M1/69),CD43 (S7), and CD93 (AA4.1) mAbs from BD PharMingen (San Diego, Calif.).Anti-mouse IgM Ab was from Jackson ImmunoResearch Laboratories, Inc.(West Grove, Pa.). Phycoerythrin-conjugated anti-mouse IL-10 mAb(JES5-16E3) was from eBioscience (San Diego, Calif.).

11.1.3 B Cell Isolation, Immunofluorescence Analysis and Cell Sorting

Blood mononuclear cells were isolated from heparinized blood aftercentrifugation over a discontinuous Lymphoprep (Axis-Shield PoC As,Oslo, Norway) gradient. Single cell splenocyte suspensions weregenerated by gentle dissection with >90% cell viability as determined bytrypan blue exclusion. Cell numbers were quantified using ahemocytometer, with relative lymphocyte percentages among viable cells(based on scatter properties) determined by flow cytometry analysis.B220- or CD19-mAb coated microbeads (Miltenyi Biotech) were used topurify spleen B cells by positive selection following the manufacturer'sinstructions. When necessary, the cells were enriched a second timeusing a fresh MACS column to obtain >99% purities.

Single cell leukocyte suspensions were stained on ice usingpredetermined optimal concentrations of each Ab for 20-60 min, and fixedas described (Sato, et al. 1996. J. Immunol. 157:4371-4378). Cells withthe light scatter properties of lymphocytes were analyzed by 2-4 colorimmunofluorescence staining and FACScan or FACSCalibur flow cytometers(Becton Dickinson, San Jose, Calif.). Dead cells were excluded from theanalysis based on their forward- and side-light scatter properties andthe use of LIVE/DEAD Fixable Dead Cell Stain Kits (Invitrogen-MolecularProbes, Carlsbad, Calif.). All histograms are shown on a 4 decadelogarithmic scale, with gates shown to indicate backgroundisotype-matched control mAb staining set with <2% of the cells beingpositive. Background staining was determined using unreactiveisotype-matched control mAbs (Caltag Laboratories, San Francisco,Calif.) with gates positioned to exclude ≧98% of unreactive cells.Spleen CD1d^(hi)CD5⁺, CD1d^(int)CD5⁻, CD1d^(lo)CD5⁻ B cells wereisolated using a FACSVantage SE flow cytometer (Becton Dickinson, SanJose, Calif.) with ˜75%-95% purities.

11.1.4 Analysis of IL-10 Production

Intracellular IL-10 analysis by flow cytometry was as described (Yanaba,et al. 2008. Immunity 28:639-650). Briefly, isolated leukocytes orpurified cells were resuspended (2×10⁶ cells/ml) in complete medium[RPMI 1640 media containing 10% FCS, 200 μg/ml penicillin, 200 U/mlstreptomycin, 4 mM L-Glutamine, and 5×10⁻⁵ M 2-mercaptoethanol (all fromGibco, Carlsbad, Calif.)] with LPS (10 μg/ml, Escherichia coli serotype0111: B4, Sigma), PMA (50 ng/ml; Sigma), ionomycin (500 ng/ml; Sigma),and monensin (2 μM; eBioscience) for 5 h, in 24-well flat-bottom plates.In some experiments, the cells were incubated for 48 hours with LPS (10μg/ml) and/or anti-mouse CD40 mAb (1 μg/ml), and/or anti-mouse IgM Ab(10 mg/ml, Jackson ImmunoResearch Laboratories, Inc, West Grove, Pa.).For analysis of cell proliferation, leukocytes were stained with CFSEVybrant™ CFDA SE fluorescent dye (0.1 μM; CFSE; Invitrogen-MolecularProbes) according to the manufacturer's instructions. For IL-10detection, Fc receptors were blocked with mouse Fc receptor mAb (2.4G2;BD PharMingen) with dead cells detected by using a LIVE/DEAD® FixableGreen Dead Cell Stain Kit (Invitrogen-Molecular Probes) before cellsurface staining. Stained cells were fixed and permeabilized using aCytofix/Cytoperm kit (BD PharMingen) according to the manufacturer'sinstructions and stained with phycoerythrin-conjugated mouse anti-IL-10mAb. Leukocytes from IL-10^(−/−) mice served as negative controls todemonstrate specificity and to establish background IL-10 staininglevels.

Secreted IL-10 was quantified by ELISA. Purified B cells (4×10⁵) werecultured in 0.2 ml of complete medium in a 96-well flat-bottom tissueculture plates. Culture supernatant fluid IL-10 concentrations werequantified using IL-10 OptEIA ELISA kits (BD PharMingen) following themanufacturer's protocols. All assays were carried out using triplicatesamples.

11.1.5 B Cell Cytokine Transcript Expression Analysis

Purified spleen B cells were cultured for 5 hours with LPS+PMA+ionomycin(L+PI). IL-10-secreting spleen B cells were identified using an IL-10secretion detection kit (Miltenyi Biotech, Auburn, Calif.) withsubsequent staining for CD19 expression before cell sorting intoIL-10⁺CD19⁺ and IL-10⁻CD19⁺ populations. Total RNA was extracted fromthe purified B cells using TRIzol (Invitrogen-Molecular Probes), withrelative cytokine transcripts quantified by GeneChip analysis(Affymetrix Mouse Genome 430 2.0 GeneChips; Affymetrix, Santa Clara,Calif.). All quality parameters for the arrays were confirmed to be inthe range recommended by the manufacturer.

11.1.6 Statistical Analysis

All data are shown as means (±SEM). Significant differences betweensample means were determined using the Student's t test.

11.2 Results

11.2.1 IL-10-Producing B Cells Preferentially Secrete IL-10

IL-10-Producing B Cells Preferentially Secrete IL-10

Spleen B cells that are competent to express cytoplasmic IL-10 following5 hours of L+PIM stimulation were predominantly found within theCD1d^(hi)CD5⁺CD19⁺ subset in wild type B6 mice (FIG. 17A), as described(Yanaba, et al. 2008. Immunity 28:639-650). By contrast, IL-10expressing B cells were significantly less common within theCD1d^(hi)CD5⁻, CD1d^(lo)CD5⁺, or CD1d^(lo)CD5⁻ B cell subsets (p<0.01),with B cells from IL-10^(−/−) mice used as negative controls forbackground IL-10 staining. We have previously shown that 5 hour L+PIMstimulation does not influence the phenotype of these B cell subsets(Yanaba, et al. 2008. Immunity 28:639-650; Matsushita, et al. 2008. J.Clin. Invest. 118:3420-3430). IL-10⁺CD19⁺ B10 cells were predominantlyCD21^(int/hi), CD23^(lo), CD24^(hi), CD43^(+/−), and CD93^(−/−) (AA4.1)(FIG. 17B). Thereby, spleen B10 cells are relatively rare and share someoverlapping phenotypic markers with the B-1a, MZ, and T2-MZ precursor Bcell subsets, but are nonetheless phenotypically distinct, (Yanaba, etal. 2008. Immunity 28:639-650; Matsushita, et al. 2008. J. Clin. Invest.118:3420-3430).

Determining whether spleen B10 cells purified from wild type miceproduce only Il-10 was problematic due to the inherent technicaldifficulties when purifying such low-frequency cells and thepredominantly low level induction of most cytokines by B cells. However,spleen B10 cell frequencies and numbers are expanded in mice expressinga human CD19 transgene (hCD19Tg, FIG. 17C) (Yanaba, et al. 2008.Immunity 28:639-650). Within the CD1d^(hi)CD5⁺ B cell subset in hCD19Tgmice, 58% of the cells were induced to express cytoplasmic IL-10following L+PIM stimulation for 5 h, but were significantly less commonwithin the CD1d^(hi)CD5⁻, CD1d^(lo)CD5⁺, or CD1d^(lo)CD5⁻ B cell subsets(p<0.01). Whether IL-10-competent B cells represent a heterogeneouspopulation capable of producing other cytokines was therefore examinedby purifying IL-10-secreting CD19⁺ B cells from hCD19Tg mice (FIG. 17D).IL-10 transcripts were expressed at ˜6-fold higher frequencies inIL-10-secreting B cells when compared with B cells that did not secretedetectable IL-10 (FIG. 17E). Furthermore, IL-10⁺ B cells did not producetranscripts for 31 additional cytokines at levels higher than IL-10⁻ Bcells under these culture conditions. Thus, the IL-10-secretingCD1d^(hi)CD5⁺ B10 cell subset was phenotypically and functionallyunique.

11.2.2 B10 Cell Numbers During Development

To characterize B10 cell development, the frequencies and numbers ofspleen CD1d^(hi)CD5⁺ B cells and IL-10-producing B cells were assessedin neonatal, 2-mo-old, and 6-mo-old wild type B6 mice. CD1d^(hi)CD5⁺ Bcells were virtually absent in neonatal spleen, with 5-fold lowerfrequencies than in 2-mo-old mice, (FIG. 18A). Remarkably, neonatalspleen had 6.8-fold higher frequencies of IL-10-producing B cells thanthe 1-2% frequency induced in 2-mo-old wild type spleen B cellsfollowing 5 hour L+PIM stimulation (FIG. 18B). Nonetheless, the majorityof IL-10⁺ B cells in neonates had a CD1d^(lo)CD5⁺ phenotype, with6.5-fold higher CD5 expression levels than IL-10⁻ B cells (p<0.001, FIG.18C). Conversely, the frequencies and numbers of CD1d^(hi)CD5⁺ B cellswere 1.4- and 1.8-fold higher in 6-mo-old mice than in 2-mo-old mice.IL-10⁺ B cell frequencies and numbers were also 1.8- and 1.6-foldhigher, respectively, in 6-mo-old mice compared with 2-mo-old mice(p<0.05). Spleen IL-10⁺ B cells from 2- and 6-mo-old mice werepredominantly CD1d^(hi)CD5⁺. Thus, neonatal IL-10-producingCD1d^(lo)CD5⁺ B cells were present at relatively high frequencies andnumbers, while CD1d^(hi)CD5⁺ B10 cells expanded with age in the spleensof adult mice.

11.2.3 B10 Cell Development is T Cell and Pathogen Independent

To identify factors that influence B10 cell development, CD1d^(hi)CD5⁺and IL-10-producing B cells were assessed in T cell-deficient nude miceand in gnotobiotic mice. CD1d^(hi)CD5⁺ B cell frequencies and numberswere ˜5-fold higher in adult nude mice than in age-matched wild typemice (p<0.05; FIG. 19A). Cytoplasmic IL-10⁺ B cell frequencies andnumbers were also ˜4.5-fold higher in L+PIM-stimulated splenocytes fromnude mice when compared with wild type mice (p<0.05; FIG. 19B). Themajority of IL-10⁺ B cells in nude and wild type mice had aCD1d^(hi)CD5⁺ phenotype, while IL-10⁻ B cells were CD1d^(lo)CD5⁻ (FIG.19C). Whether B cell IL-10 production in vitro was influenced by thepresence of T cells was also assessed by culturing whole splenocytes orpurified B cells alone with L+PIM for 5 h. The frequency of B cells thatexpressed cytoplasmic IL-10 among all B cells was comparable in bothcultures (FIG. 19D). Thus, spleen B10 cell development does not requirethe presence of T cells in nude mice.

To determine whether environmental factors influence B10 celldevelopment, germ-free mice were assessed. CD1d^(hi)CD5⁺ B cellfrequencies and numbers were similar, if not identical, in age-matchedmice reared in gnotobiotic and specific pathogen-free colonies (FIG.19E). Cytoplasmic IL-10⁺ B cell frequencies and numbers were alsosimilar (FIG. 19F) and the majority of IL-10⁺ B cells had aCD1d^(hi)CD5⁺ phenotype. Thus, environmental flora and gut-associatedbacteria are not required for spleen B10 cell development.

11.2.4 Autoimmunity Promotes B10 Cell Development

The influence of autoimmunity on B10 cell development was assessed inthe NOD, NZB/W F1, MRL/lpr, DBA/1, and SJL mouse strains. NOD mice are aspontaneous model of type 1 diabetes (Anderson, et al. 2005. Annu. Rev.Immunol. 23:447-485). DBA/1 mice develop CIA after collagen immunization(Courtenay, et al. 1980. Nature. 283:666-668). SJL mice are susceptibleto EAE after myelin proteolipid protein immunization (Dal Canto, et al.1995. Microsc. Res. Tech. 32:215-229). MRL/lpr and NZB/W micespontaneously develop lupus-like disease (Theofilopoulos, A. N., ed.1992. Murine models of lupus. Churchill Livingston, Edinburgh). Most Bcells in NOD (85±2%, n>3), MRL/lpr (80±12%, n=3), and SJL (94±1% n=3)mice expressed cell surface CD5 at levels that were significantly higherthan background control mAb staining in comparison with B cells from B6(25±2%, n>3), NZB/W (28±1%, n=3), and DBA/1 (14±1%, n=3) mice inside-by-side comparisons (FIG. 20A). Nonetheless, the frequency ofCD1d^(hi)CD5⁺ B cells was limited, but 3- to 9-fold higher in NZB/W,MRL/lpr, NOD, and SJL mice than in 2-mo-old B6 mice. CD1d^(hi)CD5⁺ Bcell numbers were also 3.8- to 5.9-fold increased in NZB/W, MRL/lpr, andNOD mice. Thus, the CD1d^(hi)CD5⁺ B cell subset increased in frequencyin mice predisposed to autoimmunity.

The numbers of cytoplasmic IL-10⁺ B cells were 2- to 4-fold higher inNZB/W, MRL/lpr, and NOD mice than in B6 wild type mice afterL+PIM-stimulation (FIG. 20B). By contrast, IL-10-producing B cellnumbers were 49% and 55% lower in DBA/1 and SJL mice, respectively,relative to wild type mice (p<0.01). In all cases, the majority ofcytoplasmic IL-10⁺ B cells also retained a CD1d^(hi)CD5⁺ phenotype (FIG.20C). Thus, B10 cell numbers were significantly higher in diabetes- andlupus-prone mice, but significantly below wild type levels in DBA/1 andSJL mice that are susceptible to exogenous autoantigen-inducedautoimmune disease.

11.2.5 Receptors that Regulate B10 Cell Development In Vivo

B cell development is regulated through the BCR and other molecules thatinform B cells of their extracellular microenvironment, including CD19,CD21, CD22, and CD40 (Tedder. 1998. Semin. Immunol. 10:259-265). Whethercell surface signals influence B10 cell development was determined byassessing CD1d^(hi)CD5⁺ and IL-10 producing B cell development inIL-10^(−/−), MD4, CD19^(−/−), CD21^(−/−), CD40^(−/−), MHC-I/II^(−/−),hCD19Tg, CD22^(−/−), CD40L/BTg, and CD40L/BTg/CD22^(−/−) mice. MD4transgenic mice have a fixed BCR specific for hen egg lysozyme (Goodnow,et al. 1988. A Nature 334:676-682). MHC-I/II^(−/−) mice are deficient incell surface MHC class II, and most MHC class I and CD1 molecules due tocombined disruption of the H2-Ab1 and β2-microglobulin genes (Grusby, etal. 1993. Proc. Natl. Acad. Sci. USA 90:3913-3917; Brutkiewicz, et al.1995. J. Exp. Med. 182:1913-1919). B cells from CD40L/BTg mice expressectopic cell surface CD40L constitutively, with some mice developinglupus-like disease (Higuchi, et al. 2002. J. Immunol. 168:9-12).

CD1d^(hi)CD5⁺ B cells were present at similar frequencies and numbers inIL-10^(−/−), wild type, and MD4 mice (FIG. 21A). However, both thefrequencies (65% decrease, p<0.01) and numbers (90% decrease, p<0.01) ofL+PIM-induced cytoplasmic IL-10⁺ B cells were reduced in MD4 mice whencompared with wild type mice (FIG. 21B). In CD19^(−/−) mice, thefrequency and number of CD1d^(hi)CD5⁺ B cells was 87-92% lower than inwild type littermates, while L+PIM-induced IL-10⁺ B cell frequencies andnumbers were 73% and 89% lower, respectively (p<0.01). By contrast,CD21- or CD40-deficiencies did not affect the frequencies or numbers ofCD1d^(hi)CD5⁺ or IL-10 producing B cells. CD1d^(hi)CD5⁺ B cellfrequencies could not be assessed in MHCI/II^(−/−) mice that do notexpress CD1d, but IL-10 producing spleen B cell frequencies and numberswere normal. Spleen CD1d^(hi)CD5⁺ B cell frequencies and numbers werenormal in MyD88^(−/−) mice (FIG. 21A), while L+PIM-induced cytoplasmicIL-10⁺ B cell frequencies and numbers were reduced by 40% and 46%,respectively, in 5 hour assays (FIG. 21B). Thus, BCR diversity, andCD19- and MyD88-generated signals were critical for normal IL-10producing CD1d^(hi)CD5⁺ B10 cell development and/or peripheral expansionin vivo, or visualization in vitro.

The frequencies and numbers of CD1d^(hi)CD5⁺ B cells were 5.8- and1.5-fold higher in hCD19Tg mice than in wild type littermates,respectively (FIG. 21A). IL-10-producing B cell frequencies and numberswere 7.9- and 2.1-fold higher in hCD19Tg mice, respectively (FIG. 21B).Similarly, the frequency and number of CD1d^(hi)CD5⁺ B cells was 2.7-and 1.9-fold higher in CD22^(−/−) mice than in wild type mice, while thefrequency and number of IL-10-producing B cells was 4.1- and 2.8-foldhigher, respectively. The frequency and number of CD1d^(hi)CD5⁺ B cellswas 1.4- and 3.9-fold higher in CD40L/BTg mice than in wild type mice,while the frequency and number of IL-10-producing B cells was 1.4- and3.7-fold higher, respectively. Thus, CD19 overexpression,CD22-deficiency, and ectopic CD40L expression on B cells significantlyenhanced B10 cell numbers in vivo.

Combined CD22-deficiency and CD40L expression dramatically expanded theB10 cell subset in CD40L/BTg/CD22^(−/−) mice (FIG. 21). The frequencyand number of CD1d^(hi)CD5⁺ B cells was 7.0- and 16-fold higher inCD40L/BTg/CD22^(−/−) mice, while the frequency and number ofIL-10-producing B cells was 11- and 26-fold higher inCD40L/BTg/CD22^(−/−) mice than in wild type mice, respectively (p<0.01).Thus, the absence of CD22 regulation combined with CD40L expression by Bcells dramatically increased B10 cell numbers in vivo. In all mouselines except MHC-I/II^(−/−) mice, L+PIM-induced IL-10⁺ B cellsmaintained a CD1d^(hi)CD5⁺ phenotype when present. Thus, spleen B10 celldevelopment or expansion in vivo is not intrinsic, but depends in parton transmembrane signals.

11.2.6 LPS and CD40 Stimulation Induce B Cell Cytoplasmic IL-10Production In Vitro

Signals that regulate B cell IL-10 production were assessed by culturingwild type spleen B cells with LPS, agonistic CD40 mAb, or mitogenicanti-IgM Ab at predetermined optimal concentrations. PMA, ionomycin, andmonensin (PIM)-stimulation for 5 hours induced cytoplasmic IL-10expression by 0.5-2% of B cells, which was 8 to 13-fold higher than formedia alone and >5-fold higher than for LPS alone (FIG. 22A). Theaddition of CD40 mAb or anti-IgM Ab to PIM-stimulated cultures did notsignificantly increase IL-10⁺ B cell frequencies. However,L+PIM-stimulation for 5 hours induced >2-fold higher frequencies ofIL-10⁺ B cells than PIM, or CD40 mAb plus PIM, or anti-IgM Ab plus PIM(p<0.01). Thus, L+PIM stimulation induced optimal B cell cytoplasmicIL-10 expression in 5 hour assays.

Culturing B cells with LPS or CD40 mAb for 48 hours with PIM addedduring the last 5 hours of culture induced significantly higherfrequencies of cytoplasmic IL-10⁺ B cells than anti-IgM Ab with PIMadded during the last 5 hours of culture (FIG. 22A). LPS stimulation wasalso significantly more robust than CD40 mAb stimulation. Unexpectedlyhowever, the combination of LPS plus CD40 mAb for 48 h, or anti-IgM Abplus either LPS or CD40 mAb, or all three together with PIM stimulationduring the last 5 hours did not increase IL-10⁺ B cell frequenciessignificantly beyond what was normally observed with 5 hour PIMstimulation alone. Thus, culturing B cells with LPS or CD40 mAb for 48hours before PIM stimulation induced the highest numbers of B cells withcytoplasmic IL-10 expression.

Spleen B cells stimulated with CD40 mAb for 48 hours plus L+PIM for 5hours did not induce significantly higher numbers of cytoplasmic IL-10⁺B cells than LPS for 48 hours plus PIM for 5 hours (FIG. 22A). However,this sequential combination of stimuli induced the most robust levels ofcytoplasmic IL-10 expression when compared with independent LPS or CD40mAb stimulation. By contrast, adding L+PIM during the last 5 hours ofanti-IgM Ab, or CD40 mAb plus anti-IgM Ab cultures only induced ˜2-foldhigher numbers of IL-10⁺ B cells than anti-IgM Ab or CD40 mAb alone.Thus, CD40 ligation with subsequent 5 hour L+PIM stimulation wasthe'most potent strategy for inducing the highest numbers of cytoplasmicIL-10⁺ B cells with the highest levels of cytoplasmic IL-10.

11.2.7 LPS but not BCR or CD40 Ligation Induces B Cell IL-10 SecretionIn Vitro

Signals that regulate B cell IL-10 secretion were assessed by culturingspleen B cells with LPS, agonistic CD40 mAb, or mitogenic anti-IgM Ab,with culture supernatant fluid IL-10 levels determined by ELISA. LPSstimulation of spleen B cells for 24 hours induced 3.5- to 3.8-fold moreIL-10 than unstimulated cells, or cells cultured with CD40 mAb oranti-IgM Ab (p<0.01; FIG. 22B). LPS stimulation alone for 72 hoursinduced significant B cell IL-10 secretion in contrast to CD40 mAb,anti-IgM Ab, or CD40 mAb plus anti-IgM Ab (p<0.01). In fact,simultaneous CD40 mAb or anti-IgM Ab treatment reduced LPS-induced IL-10secretion by >68%. Furthermore, B cells cultured with CD40 mAb, anti-IgMAb, and CD40 mAb plus anti-IgM Ab did not secrete significantly moreIL-10 when LPS was added during the last 24 hours of culture. Thus, LPSwas the most potent stimulus for inducing both IL-10 production andsecretion, while CD40-generated signals promoted cytoplasmic IL-10generation but inhibited its secretion.

11.2.8 Normal B10 Cell Development in MyD88^(−/−) mice

L+PIM-induced cytoplasmic IL-10⁺ B cell frequencies and numbers werereduced in MyD88^(−/−) mice (FIG. 21B). Whether this represented adevelopmental defect in vivo or reflected the absence of LPS-inducedIL-10 production was therefore assessed in vitro. The frequency ofcytoplasmic IL-10⁺ MyD88^(−/−) spleen B cells was also significantlyreduced after 48 hours of LPS stimulation relative to wild type B cells(FIG. 22C). By contrast, the frequency of CD40 mAb-induced cytoplasmicIL-10⁺ B cells was equivalent in MyD88^(−/−) and wild type littermates.Adding LPS to MyD88^(−/−) B cell cultures during the last 5 hours didnot increase the frequency of CD40 mAb-induced cytoplasmic IL-10⁺ Bcells. IL-10 secretion was also significantly reduced in LPS-stimulatedcultures of MyD88^(−/−)B cells (FIG. 22D). Therefore, MyD88 expressionwas not required for normal B10 cell development and/or expansion invivo, but MyD88 was required for optimal IL-10 production and secretionfollowing LPS stimulation.

11.2.9 LPS and CD40 Stimulation Promotes B Cell Competence forCytoplasmic IL-10 Production

Although CD5⁺ B cells predominate in the spleens of neonatal wild typemice (FIG. 18), IL-10 production was not constitutive since culturingneonatal spleen B cells with monensin alone did not result in detectablecytoplasmic IL-10 staining. Nonetheless, relatively high frequencies ofIL-10-producing B cells were generated after 5 hours of L+PIMstimulation (FIGS. 18 and 7A). Whether additional neonatal B cells couldbe induced to produce IL-10 was therefore assessed by culturing spleen Bcells with LPS or agonistic CD40 mAb for 48 h. IL-10⁺ B cells were 40%more frequent after prolonged LPS stimulation (p<0.05) despite lowerlevel cytoplasmic IL-10 staining (FIG. 23A). Culturing neonatalsplenocytes with CD40 mAb induced significantly fewer IL-10⁺ B cells(p<0.05). The combination of CD40 mAb for 48 hours with L+PIMstimulation during the last 5 hours of culture generated similar numbersof IL-10⁺ B cells as in the 48 hour LPS cultures, but the overallintensity of cytoplasmic IL-10 staining was highest. Therefore, themajority of CD5⁺ neonatal B cells were already competent forL+PIM-induced IL-10 production, with additional in vitro stimulationincreasing B10 cell numbers significantly.

CD1d^(hi)CD5⁺ or IL-10-competent B cells are not commonly observed inthe blood or peripheral lymph nodes of naïve wild type mice, even after5 hours of L+PIM stimulation in vitro (FIG. 23B). Whether prolonged LPSor CD40 stimulation could induce B cell competence for IL-10 productionwas therefore examined. LPS or agonistic CD40 mAb stimulation induced6-9-fold higher frequencies of cytoplasmic IL-10⁺ B cells in 48 hourcultures than in 5 hour L+PIM cultures (p<0.01; FIG. 23B). Thecombination of CD40 mAb for 48 hours with L+PIM stimulation during thelast 5 hours of culture also generated high numbers of IL-10⁺ B cellswith the highest intensity of cytoplasmic IL-10 staining. Similarresults were obtained using peripheral lymph node B cells. These resultssuggest that prolonged LPS or CD40 stimulation can promote thematuration of CD5⁻ progenitor B10 cells into an IL-10 competent state.

Whether LPS or CD40 generated signals induce B cells to express aCD1d^(hi)CD5⁺ phenotype was therefore assessed. Neonatal spleen, andadult blood and spleen B cells were cultured with LPS or agonistic CD40mAb for 48 hours and examined for CD1d and CD5 expression byimmunofluorescence staining. CD40 mAb but not LPS stimulation inducedmarkedly higher CD5 expression on most B cells (FIG. 23C). By contrast,B cell CD1d expression was not induced or changed by LPS or CD40 mAbstimulation or the combination of both treatments for 48 h. Thus, CD5was an induced marker for CD40-stimulated B10 cells.

11.2.10 IL-10 Production by Adult Spleen B Cells is Restricted to theCD1d^(hi)CD5⁺ B Cell Subset

Splenic B10 cells that express cytoplasmic IL-10 after L+PIM stimulationlocalize primarily within the CD1d^(hi)CD5⁺ subset (FIG. 17A). It wastherefore determined whether the increased frequency of IL-10⁺ B cellsin LPS or CD40 stimulated cultures results from the maturation of B10cell progenitor cells within the CD1d^(hi)CD5⁺ subset or other B cellpopulations. Spleen CD1d^(hi)CD5⁺ or non-CD1d^(hi)CD5⁺ B cells from wildtype mice were purified and cultured with LPS for 48 h, or withagonistic CD40 mAb for 48 hours with LPS added during the last 5 hoursof culture. The CD1d^(hi)CD5⁺ B cell subset from B6 mice normallycontains ˜9-18% IL-10⁺ B cells after 5 hours of L+PIM stimulation (FIG.17A). However, 33-43% of the CD1d^(hi)CD5⁺ B cells expressed cytoplasmicIL-10 after 48 hour LPS or CD40 mAb stimulation, whereas <3% ofCD1d^(lo)CD5^(−/−) B cells produced IL-10 (FIG. 24A). Thus, splenic Bcells capable of producing IL-10 after prolonged LPS or CD40 mAbstimulation predominantly derive from the CD1d^(hi)CD5⁺ subset.

To determine whether the increased frequency of IL-10⁺ B cells after LPSor CD40 stimulation results from the clonal expansion of existingIL-10-competent B cells or maturation of progenitor B10 cells, IL-10⁺ Bcell proliferation was assessed by labeling purified spleen B cells withCFSE before LPS or CD40 mAb stimulation in vitro. LPS stimulation for 48hours induced IL-10⁺ and IL-10⁻ B cell proliferation, although IL-10⁺ Bcells proliferated more than IL-10⁻ B cells as measured by reduced CFSEstaining (FIG. 24B). By contrast, CD40 mAb stimulation for 48 hours plusLPS treatment for the last 5 hours of culture only induced modest IL-10⁺or IL-10⁻ B cell proliferation during these 48 hour cultures. CD40 mAbstimulation predominantly induces B cell clonal expansion between 72-96hours as described (Poe, et al. 2004. Nat. Immunol. 5:1078-1087;Brutkiewicz, et al. 1995. J. Exp. Med. 182:1913-1919). Thus, LPSstimulation induces and expands the IL-10⁺ B cell subset during 48 hourcultures, while CD40 ligation induces B cell competence for cytoplasmicIL-10 production (FIG. 24C).

11.3 Discussion

The majority of adult spleen B cells that were competent for IL-10production after 5 hour L+PIM stimulation were found within theCD1d^(hi)CD5⁺ subset (FIG. 17A). IL-10⁺ B10 cells preferentiallyproduced IL-10 transcripts relative to other B cells, but did not appearto preferentially produce other known cytokines (FIG. 17E).IL-10-competent B cells were also found within the CD1d^(hi)CD5⁻ andCD1d^(int)CD5⁺ subsets, but at significantly lower (p<0.05) frequenciesand numbers than in the CD1d^(hi)CD5⁺ subset. Spleen CD1d^(hi)CD5⁺ Bcells also exist that could acquire IL-10 competence in vitro after 48hour stimulation with LPS or agonistic CD40 mAb (FIGS. 22A and 24A),potentially reflecting their maturation. By contrast, spleenCD1d^(lo)CD5⁻ B cells were not rendered IL-10 competent after 48 hourstimulation with LPS or agonistic CD40 mAb (FIG. 24A). Progenitor B10cells may also exist that do not express CD5 or CD1d, yet can be inducedto express IL-10 in vitro. Specifically, the vast majority of blood andlymph node B cells in adult mice were CD1d^(lo)CD5⁻ and did not expressIL-10 after 5 hour L+PIM stimulation (FIG. 23B). However, a small subsetof blood and lymph node B cells acquired IL-10 competence after 48 hourCD40 ligation and/or LPS exposure. Neonatal spleen B cells predominantlyexpressed CD5 and were almost exclusively CD1d^(lo), but ˜14% wereinduced to express cytoplasmic IL-10 after 5 hour L+PIM exposure (FIG.18). Consistent with this, neonatal and adult B cells uniformlyupregulated CD5 expression after CD40 ligation in vitro (FIG. 23C).Thereby, L+PIM stimulation may induce IL-10 production in small subsetsof B cells that have received appropriate competence-inducing signals invivo or in vitro regardless of their maturation. Alternatively,CD1d^(lo)CD5⁻ progenitor B10 cells may be induced to mature, expressCD5, and acquire competence for activation-induced cytoplasmic IL-10production as proposed in the maturation scheme outlined in FIG. 24C.Factors that regulate or induce CD1d expression by some spleen B cellsare unknown. Thus, IL-10 competence and the CD1d^(hi)CD5⁺ phenotypedefine the spleen B10 cell subset, but may also reflect theirmaturation, activation status, subset commitment, and/or tissuelocalization.

Development, maturation, and/or expansion of the spleen B10 cell subsetrequired specific external signals. BCR specificity significantlyinfluenced B10 cell development, with B10 cell numbers reduced by 90% intransgenic mice expressing a fixed Ag-receptor (FIG. 21B). In contrast,B10 cell development did not require the presence of T or NKT cells(FIG. 19). Furthermore, CD1, MHC class I and class II, CD21, or CD40expression were not required for normal B10 cell development or IL-10induction (FIG. 21). Nonetheless, CD40 ligation induced cytoplasmicIL-10 production by B cells in vitro (FIG. 22) and ectopic CD154expression by B cells in CD40L/BTg mice increased B10 cell numbers by 3-to 4-fold (FIG. 21). Thereby, CD40:CD154 interactions may facilitate B10cell maturation under some conditions, but were not required for B10cell acquisition of IL-10-competence in vivo. TLR signaling was alsocritical for B10 cell effector function since LPS induced B10 cells toboth produce and secrete IL-10 in vitro, while CD40 ligation onlyinduced cytoplasmic IL-10 production (FIG. 22). B10 cell development wasnormal in MyD88^(−/−) mice (FIG. 22 C-D), but LPS-induced IL-10production and secretion were significantly reduced in MyD88^(−/−)Bcells (FIG. 22D). A need for MyD88 in LPS-induced B10 cell function mayexplain why mice containing only MyD88^(−/−) B cells develop chronic EAE(Lampropoulou, et al. 2008. J. Immunol. 180:4763-4773). Thus,intertwined innate and adaptive signals may regulate B10 cell maturationand effector function rather than independently regulating distinctfollicular, MZ, and B-1a regulatory B cell subsets.

The B10 cell subset expanded significantly in response to enhanced Bcell signaling in vivo, while retaining their CD1d^(hi)CD5⁺ phenotype.B10 cell numbers were significantly expanded in hCD19Tg mice, but weredramatically reduced in CD19^(−/−) mice (FIG. 21). B10 cell numbers werealso increased 2- to 3-fold in CD22^(−/−) mice (FIG. 21). CD19 regulatesa Lyn kinase amplification loop (Fujimoto, et al. 1999. Immunity11:191-200; Fujimoto, et al. 2000. Immunity 13:47-57) that enhancestransmembrane signals (Yazawa, et al. 2003. Blood 102:1374-1380; Poe, etal. 2001. Int. Rev. Immunol. 20:739-762; Tedder, et al. 2005. Curr. Dir.Autoimmunity 8:55-90), while CD22 dampens B cell and CD19 signaltransduction through the recruitment of SHP-1 and SHIP phosphatases(Fujimoto, et al. 1999. Immunity 11:191-200; Poe, et al. 2001. Int. Rev.Immunol. 20:739-762), resulting in elevated cell surface CD5 expressionby B cells in CD22^(−/−) B6 mice (Poe, et al. 2004. J. Immunol.172:2100-2110). Spleen B10 cells were also significantly expanded inCD40L/BTg mice, with a 26-fold increase in CD22^(−/−)CD40L/BTg micewhere up to 20% of spleen B cells were B10 cells (FIG. 21). Since CD22negatively regulates CD40 signaling (Poe, et al. 2004. Nat. Immunol.5:1078-1087; Poe, et al. 2004. J. Immunol. 172:2100-2110), enhanced CD40function may drive B10 cell expansion and/or survival inCD22^(−/−)CD40L/BTg mice (Higuchi, et al. 2002. J. Immunol. 168:9-12;van Kooten, et al. 2000. J. Leukoc. Biol. 67:2-17). Although spleen B1acells were also expanded in hCD19Tg (3-fold), CD40L/BTg (4.2-fold), andCD22^(−/−)CD40L/BTg (3-fold) mice, these frequencies did not parallelB10 cell expansion. Thus, the B10 cell subset responds significantly totransmembrane signals in vivo.

Spleen B10 cell numbers were increased in mice predisposed to developautoimmunity. B10 cell numbers expanded significantly in the NZB/W F1and MRL/lpr mouse models of lupus and the NOD model of diabetes evenbefore obvious autoantibodies and signs of disease were apparent (FIG.20, data now shown). B10 cell numbers are significantly expanded inCD40L/BTg mice (FIG. 21), although some develop lupus-like disease(Higuchi, et al. 2002. J. Immunol. 168:9-12). Spleen B10 cell numberswere also significantly higher in 6 mo-old C57BL/6 mice relative to 2mo-old mice (FIG. 18), which may combat the development of autoimmunitywith age. By contrast, B10 cell numbers were significantly lower in theDBA/1 and SJL mouse models of autoantigen-inducible autoimmunity, wherethe relative paucity of B10 cells may prevent effective toleranceinduction. Thereby, B10 cell expansion may suppress autoimmunity, incontrast to B1a cells that contribute to autoimmune disease (Hayakawa,et al. 1986. Eur. J. Immunol. 16:450-456). As a result, these autoimmunediseases may be worse in the absence of B10 cells as occurs when all Bcells are depleted during CHS and EAE (Yanaba, et al. 2008. Immunity28:639-650; Matsushita, et al. 2008. J. Clin. Invest. 118:3420-3430).Since B10 cell numbers are dynamic, change during development, andincrease with age and autoimmunity, alterations in the balance betweenB10 cell negative regulation and B cell positive contributions to immuneresponses are likely to vary in different diseases and during the courseof disease (Bouaziz, et al. 2008. Immunol. Rev. 224:201-214).

Spleen B10 cells and their potential progenitors (FIG. 24C) can accountfor many of the in vivo activities previously attributed to regulatory Bcells (Bouaziz, et al. 2008. Immunol. Rev. 224:201-214; Yanaba, et al.2008. Immunity 28:639-650; Matsushita, et al. 2008. J. Clin. Invest.118:3420-3430). Specifically, BCR and CD40 engagement are required forregulatory B cell functions in CIA, CHS, and EAE models (Fillatreau, etal. 2002. Nat. Immunol. 3:944-950; Evans, et al. 2007. J. Immunol.178:7868-7878; Yanaba, et al. 2008. Immunity 28:639-650; Matsushita, etal. 2008. J. Clin. Invest. 118:3420-3430), and functional B10 cellsrequired diverse BCRs (FIG. 21) and in vivo Ag sensitization (Yanaba, etal. 2008. Immunity 28:639-650; Matsushita, et al. 2008. J. Clin. Invest.118:3420-3430) for their generation. Stimulating naïve or autoimmunespleen B cells in vitro with LPS or agonistic CD40 mAb also gives riseto regulatory B cells that inhibit or prevent autoimmunity (Mauri, etal. 2003. J. Exp. Med. 197:489-501; Tian, et al. 2001. J. Immunol.167:1081-1089). That CD40 ligation induced IL-10-competance in bothCD1d^(hi)CD5⁺ and some CD1d^(int)CD5⁻ B cells (FIG. 22) may also explainhow agonistic CD40 mAbs reduce inflammation in the CIA model ofrheumatoid arthritis (Mauri, et al. 2000. Nat. Med. 6:673-679). LPSinduction of B10 cell competence for IL-10 production and secretion(FIG. 22C) may also explain why LPS pretreatment modulates the course ofdisease in EAE (Buenafe, et al. 2007. J. Neuroimmunol. 182:32-40).Similarly, B cells activated with LPS in vitro can protect NOD mice invivo, although this effect was not attributed to B cell IL-10 production(Tian, et al. 2001. J. Immunol. 167:1081-1089). Thus, B10 cells andregulatory B cells identified in previous studies were similar in theirresponses to polyclonal stimuli such as LPS and CD40.

That BCR diversity was required for B10 cell development in vivo (FIG.21) supports observations that B10 cell and regulatory B cell functionis Ag-specific (Fillatreau, et al. 2002. Nat. Immunol. 3:944-950;Yanaba, et al. 2008. Immunity 28:639-650; Matsushita, et al. 2008. J.Clin. Invest. 118:3420-3430). The activation of arthritogenicsplenocytes with collagen alone (Evans, et al. 2007. J. Immunol.178:7868-7878) or collagen plus agonistic CD40 mAb in vitro gives riseto IL-10 producing B cells that prevent arthritis (Mauri, et al. 2003.J. Exp. Med. 197:489-501). Autoreactive B cell production of IL-10during EAE also requires simultaneous autoantigen and CD40 stimulation(Fillatreau, et al. 2002. Nat. Immunol. 3:944-950). Transfusions ofBCR-activated B cells also protects NOD mice from type 1 diabetes in anIL-10-dependent manner (Hussain, et al. 2007. J. Immunol.179:7225-7232). However, BCR ligation using mitogenic Ab in vitronegatively regulated cytoplasmic and secreted IL-10 production whencombined with LPS or CD40 mAb during in vitro cultures, although BCRligation alone induced some B cells to express IL-10 at higher thanbackground levels (FIG. 22). These results contrast with the findings ofothers that BCR ligation using anti-Igic Ab does not affect simultaneousLPS-induced IL-10 secretion by splenic transitional, follicular, andmarginal zone B cells, B1 B cells from the peritoneal cavity, or lymphnode B cells (Lampropoulou, et al. 2008. J. Immunol. 180:4763-4773).However, the strength, nature, or timing of BCR generated signalsrequired for evoking B10 cell development or function may bespecifically regulated in vivo. For example, BCR engagement by potentforeign Ags may inhibit'B10 cell clonal expansion or divert B10progenitor cells along a distinct functional pathway, while BCR signalsgenerated by self Ags may promote their expansion. Thereby, LPS or othersignals may optimally induce B10 cell effector function (IL-10secretion) after Ag-selection or CD40-induced maturation in vivo.

It remains difficult to distinguish the relationships between spleenB10, B-1a, and MZ B cells due to their shared phenotypic markers andpotentially overlapping developmental pathways. For example, microbialcolonization and conventional T cells were not required for spleen B10,B-1a, or CD1d^(hi) MZ B cell development, and all three subsets requireCD19 expression (FIGS. 19 and 21). However, spleen CD5⁺ andIL-10-competent B cells were present at high frequencies in newborns,while the splenic CD1d^(hi) subset was not detectable in newborns (FIGS.17-18) but develops between 3-7 wks after birth (Makowska, et al. 1999.Eur. J. Immunol. 29:3285-3294). Spleen B10 cell proliferation was alsomore robust following LPS stimulation than for IL-10⁻ B cells (FIG.24B). MZ B cells also expand and provide protection early duringpathogen challenge (Martin, et al. 2001. Immunity 14:617-629).Furthermore, some IL-10 producing cells can be induced within the spleenCD1d^(hi)CD5⁻ and CD1d^(lo)CD5⁺ subsets (FIG. 17A), but it is hard todiscern whether these cells represent contaminating B10 cells or areprogenitor B10 cells that have not fully upregulated CD1d or CD5expression (FIG. 24C). Therefore, it is likely that spleen B-1a and MZ Bcells represent subsets of mixed origins, with B10 cells representingeither a distinct subset with shared phenotypic markers, or a subsetrepresenting different branches of a common lineage.

These studies address the ambiguity regarding a major B cell subset thatregulates inflammation and autoimmune disease. Evidence for theexistence of a distinct natural B10 cell subset that generallysuppresses immune responses was not uncovered. Rather, the current dataindicate that BCR and other signals are central to B10 cell generationand that polyclonal signals such as CD40 and LPS can induce theirmaturation and/or regulatory functions. Thereby, immature CD5^(+/−)progenitor B10 cells may be induced to mature and express CD5 and CD1dthrough Ag selection, potentially involving CD40 signals that inducedCD5 expression (FIG. 23C). BCR ligation is also well characterized toinduce CD5 expression (Cong, et al. 1991. Int. Immunol. 3:467). ThatCD40 ligation induces cytoplasmic IL-10 production but not significantcytokine secretion is likely to represent another critical regulatorycheckpoint in B10 cell function. Although regulatory B cells and B10cells have been predominantly described in mouse models whereautoantigen plus TLR-agonist-containing adjuvants induce autoimmunity,B10 cells also significantly influence CHS inflammation, where diseaseis independent of adjuvant challenge (Yanaba, et al. 2008. Immunity28:639-650). Thus, stimuli in addition to LPS are likely to alsoregulate IL-10 secretion by B10 cells. Although B10 cell development andtolerance regulation are undoubtedly more complex, the current resultsprovide a potential framework (FIG. 24C) for further characterizing B10cell development.

12. EXAMPLE 7 Regulatory B Lymphocyte Elimination Enhances LymphomaDepletion During CD20 Immunotherapy

Non-Hodgkin's lymphoma therapy commonly involves the use of CD20monoclonal antibody (mAb) to deplete tumor cells. Herein, the depletionof a rare CD1d^(high)CD5⁺ regulatory B cell subset (B10 cells), but notconventional B cells, significantly influenced lymphoma depletionthrough IL-10-dependent mechanisms. Thus, CD20 mAb-sensitive regulatoryB cells are potent negative regulators of tumor depletion in vivo andmay represent a new therapeutic target for treating lymphoma and othercancers.

12.1 MATERIALS AND METHODS

12.1.1 Mice

C57BL/6 and IL-10^(−/−) (B6.129P2-Il10^(tmlCgn)/J) were fromNCI-Frederick Laboratory (Frederick, Md.). CD20^(−/−) mice were asdescribed (Uchida, et al. Int. Immunol. 16, 119-129 (2004)). Mice werehoused in a specific pathogen-free barrier facility and first used at6-10 weeks of age. The Duke University Animal Care and Use Committeeapproved all studies.

12.1.2 Cell Isolation and Immunofluorescence Analysis

CD20 expression was visualized using biotin-conjugated mouse CD20(MB20-11) mAbs (Uchida, et al. Int. Immunol. 16, 119-129 (2004)) plusphycoerythrin-Cy5 (PE-Cy5) streptavidin (eBioscience, San Diego,Calif.). Other mAbs included: B220 (RA3-6B2), CD5 (53-7.3), CD1d (1B1),CD19 (1D3), and CD154 (MR1) from BD Biosciences (San Diego, Calif.).CD11b (M1/70), CD86 (GL1), F4/80 (BM8), and IL-10 (JES5-16E3) mAbs werefrom eBioscience. Anti-mouse IgM (1B4B1) antibody was from SouthernBiotechnology Associates (Birmingham, Ala.). For immunofluorescenceanalysis, single cell suspensions (10⁶ cells) were stained at 4° C.using predetermined optimal concentrations of mAb for 30 minutes asdescribed (Sato, et al. J. Immunol. 157, 4371-4378 (1996)). Single-cellsuspensions of spleen were generated by gentle dissection. Blooderythrocytes were lysed after staining using FACS™ Lysing Solution(Becton Dickinson, San Jose, Calif.). Cells with the light scatterproperties of lymphoma cells or lymphocytes were analyzed byimmunofluorescence staining with flow cytometry gating on live lymphomacells or lymphocytes as identified by forward/side light scatter. ForIL-10 detection, spleen or BL3750 cells were resuspended (2×10⁶cells/ml) in complete medium [RPMI 1640 media (Cellgro, Herndon, Va.)containing 10% FCS (Sigma, St. Louis, Mo.), 200 μg/ml penicillin, 200U/ml streptomycin, 4 mM L-Glutamine (all Cellgro), and 55 μM2-mercaptoethanol (Invitrogen, Carlsbad, Calif.)] with LPS (10 μg/ml,Escherichia coli serotype 0111: B4, Sigma), PMA (50 ng/ml; Sigma),ionomycin (500 ng/ml; Sigma), and monensin (2 μM; eBioscience) for 5 h.Before cell surface staining, Fc receptors were blocked using anti-mouseFc receptor mAb (2.4G2; BD PharMingen), and dead cells were labeledusing a LIVE/DEAD® Fixable Green Dead Cell Stain Kit(Invitrogen-Molecular Probes). Stained cells were fixed andpermeabilized using a Cytofix/Cytoperm kit (BD PharMingen) according tothe manufacturer's instructions and stained withphycoerythrin-conjugated mouse anti-IL-10 mAb. Splenocytes fromIL-10^(−/−) mice served as negative controls to demonstrate specificityand to establish background IL-10 staining levels.

12.1.3 Lymphoma Model

BL3750 lymphoma cells were as previously described (Minard-Colin, et al.Blood 112, 1205-1213 (2008)). Briefly, BL3750 cells were isolated fromlymph nodes of a single C57BL/6 cMycTG^(+/−) mouse and cultured for 7days before freezing in aliquots at −70° C. For each experiment, tumorcells were thawed and expanded for 24-48 hours in complete medium (RPMI1640 media containing 20% fetal bovine serum, 100 U/ml penicillin, 100μg/ml streptomycin, 2 mM L-glutamine, and 55 μM 2-mercaptoethanol).BL3750 cells in 250 μl PBS were injected subcutaneously into the dorsalskin of recipient mice on day 0. Mice were then given purified mAb in250 μl of PBS intravenously, and were monitored daily starting at day 7for tumor development and progression, and mortality. Tumor size wasmeasured tri-weekly using a calibrated micrometer. For tumormeasurements, the greatest longitudinal diameter was designated as L,and the greatest transverse diameter designated as W. The two chosenmeasurements were perpendicular to each other and in a plane tangentialwith the body wall. Tumor volumes (TV) was calculated as follow:TV=[(W)²×L]/2. All mice were euthanized when exhibiting distress ortumor volumes exceeding 2.0 cm³ with the date of euthanasia recorded asthe date of death from disease.

12.1.4 CD20 Immunotherapy

Sterile mouse anti-mouse CD20 mAb (MB20-11, IgG2c) and unreactive mousecontrol IgG2a mAb were produced in vitro (Uchida, et al. Int. Immunol.16, 119-129 (2004)) and purified by protein A affinity chromatography(Amersham, Arlington Heights, Ill.). All mAbs were endotoxin free(Pyrogent Plus test kit, sensitivity of 0.06 EU/mL, Cambrex Bio Science,Walkersville, Md.).

12.1.5 Cell Sorting and Adoptive Transfer Experiments

Naïve CD20^(−/−) or IL-10^(−/−)CD20^(−/−) mice were used as B celldonors. Splenic B cells were first enriched using CD19 mAb-coatedmicrobeads kits (Miltenyi Biotech, Auburn, Calif.) according to themanufacturer's instructions. In addition, CD1d^(high)CD5⁺ andCD1d^(low)CD5⁻ B cells were isolated using a FACSVantage SE flowcytometer (Becton Dickinson) with purities of 95-98%. Afterpurification, 2×10⁶ cells were immediately transferred intravenouslyinto C57BL/6 mice. In some experiments, mice were used that had survivedfor 30-45 days after tumor challenge (10⁵ BL3750 cells on day 0) andCD20 mAb treatment (250 μg on day 1). Similar results were obtained whenthe donor B cells were isolated from naïve mice or mice that hassurvived BL3750 challenge so all results were pooled.

12.1.6 Statistical analysis

Statistical comparisons of survival using the Log-Rank test and thegeneration of Kaplan-Meier cumulative survival plots used Prism software(version 4.0; GraphPad Software, San Diego, Calif.).

12.2 Results

The role of B cells during lymphoma depletion was examined in mice withintact immunity using primary CD20⁺ BL3750 lymphoma cells (FIG. 25 a)isolated from a Eμ-cMycTG^(+/−) mouse as described (Minard-Colin, et al.Blood 112, 1205-1213 (2008)). BL3750 cells provide a syngeneic mousemodel for quantifying the response of Burkitt's-like lymphoma cells toCD20 immunotherapy in vivo (Uchida, et al. J. Exp. Med. 199, 1659-1669(2004)). A single dose of mouse anti-mouse CD20 mAb but not control mAb(250 μg/mouse) depletes >95% of mature B cells after 2 days in wild typemice, with the effect lasting up to 8 weeks (FIG. 25 b) (Uchida, et al.Int. Immunol. 16, 119-129 (2004); Hamaguchi, et al. J. Immunol. 174,4389-4399 (2005)). Wild type mice given 10⁵ BL3750 cells on day 0developed detectable tumors at the site of injection by 12-19 days, witha median survival of 31 days (range 27-39, FIG. 25 c). CD20 mAb given 1day after BL3750 cell transfer depleted normal B cells and had asignificant therapeutic effect on tumor growth, with 89% of miceremaining disease free for ≧60 days (p<0.0001). Transplantation of 10⁶BL3750 cells resulted in death of all control mAb-treated mice (median25 days, range 21-29), with CD20 mAb treatment on days 1 and 7 delayingtumor growth (FIG. 25 d) and extending median survival to 34 days(p<0.0001; FIG. 25 c). This homologous tumor model was therefore used todetermine whether endogenous normal B cells influence CD20 mAb-inducedanti-tumor responses.

CD20 mAb does not deplete blood or tissue B cells in CD20^(−/−) mice(FIG. 25 b), which have normal B cell and immune system development(Uchida, et al. Int. Immunol. 16, 119-129 (2004)). Nonetheless, CD20 mAbhad a therapeutic benefit in CD20^(−/−) mice given 10⁵ CD20⁺ BL3750cells, with 50% of mice remaining disease free for up to 60 days(p<0.001; FIG. 25 c). However, this anti-tumor response was lesseffective than in wild type littermates. Moreover, tumor growth and thesurvival of CD20^(−/−) mice given 10⁶ BL3750 cells were equivalent aftercontrol (median 31 days, range 23-36) or CD20 (median 28 days, range23-40) mAb treatments (FIG. 25 c-d). Reduced tumor clearance inCD20^(−/−) mice was not expected since circulating CD20 mAb levelspersist longer in CD20^(−/−) mice than in wild type littermates(Hamaguchi, et al. J. Immunol. 174, 4389-4399 (2005)). In addition,lymphoma and normal B cell depletion in vivo is mediated by monocytesthrough antibody dependent cellular cytotoxicity, and CD20^(−/−) micehave normal monocyte numbers (Minard-Colin, et al. Blood 112, 1205-1213(2008); Uchida, et al. J. Exp. Med. 199, 1659-1669 (2004)). Thus, thepersistence of endogenous B cells inhibited the anti-tumor effects ofCD20 mAb in vivo.

To determine whether regulatory B10 cells could inhibit the anti-tumoreffects of CD20 mAb in vivo, the effect of lymphoma progression on B10cell frequencies was examined using published methods (Yanaba, et al.Immunity 28, 639-650 (2008); Matsushita, et al. J. Clin. Invest. 118,3420-3430 (2008)). B10 cells represent a small IL-10-competent subsetwithin the rare CD1d^(high)CD5⁺ subset of spleen B cells (FIG. 25 e).IL-10^(−/−) B cells served as negative controls for IL-10 staining andBL3750 cells did not produce detectable IL-10. Remarkably,IL-10-producing B10 cell frequencies increased 2-fold in tumor-bearingwild type (day 28) mice in comparison to wild type littermates orCD20^(−/−) mice without tumors. The effect of adoptively transferred B10cells on monocyte activation was also examined in vivo since macrophagesexpress IL-10 receptors at high-levels (Moore, et al. Annu. Rev.Immunol. 19, 683-765 (2001)) and mediate the depletion of CD20mAb-coated B cells and tumor cells through antibody-dependent cellularcytotoxicity (ADCC) (Minard-Colin, et al. Blood 112, 1205-1213 (2008);Uchida, et al. J. Exp. Med. 199, 1659-1669 (2004)). SpleenCD1d^(high)CD5⁺ B cells were purified from CD20^(−/−) mice andtransferred into wild type mice that were given CD20 mAb one day laterto induce monocyte-mediated ADCC. Within the CD1d^(hi)CD5⁺ B cell subsetof wild type and CD20^(−/−) mice, 9-11% of the cells were cytoplasmicIL-10 competent, while few CD1d^(lo)CD5⁻ B cells expressed IL-10(p<0.01; FIG. 26 a). Forty-eight hours after CD20 mAb treatment,CD11b⁺F4/80⁺ macrophage expression of major histocompatibility (MHC)class II molecules and CD86 was significantly higher (p<0.05, FIG. 26b). However, activation marker expression was significantly reduced inmice given CD20^(−/−)CD1d^(high)CD5⁺ B cells prior to CD20 mAb treatmentwhen compared with littermates given CD20 mAb alone (FIG. 26 b).Thereby, CD20 mAb-induced monocyte activation was significantly reducedin the presence of CD1d^(hi)CD5⁺ B cells.

Since B10 cell numbers increased with tumor progression and B10 cellsinhibited macrophage activation in vivo, the effect of B10 cells ontumor killing was assessed using adoptive transfer experiments.CD1d^(high)CD5⁺ B cells or conventional non-CD1d^(high)CD5⁺ B cells fromCD20^(−/−) mice were transferred into wild type recipients given BL3750cells one day later (day 0), followed by CD20 or control mAb treatmenton days 1 and 7. CD20 mAb treatment of wild type mice delayed tumorgrowth and prolonged survival (median 34 days, range 21-39; p<0.0001;FIG. 26 c upper panels). However, the adoptive transfer of CD20^(−/−)CD1d^(high)CD5⁺ B cells into wild type mice eliminated the therapeuticbenefit of CD20 mAb treatment (median 24 days, range 21-26), whileCD1d^(high)CD5⁺ B cells purified from IL-10^(−/−) CD20^(−/−) mice werewithout effect (FIG. 26 c lower panels). Tumor growth and mouse survivalwere not affected by the adoptive transfer of CD1d^(low)CD5⁻ B cellsfrom CD20^(−/−) or IL-10^(−/−) CD20^(−/−) mice (FIG. 26 c). Thus, B10cells negatively regulated lymphoma depletion through IL-10 production.

12.3 Discussion

The current study demonstrates that B10 cells are potent negativeregulators of tumor depletion by CD20 mAb in vivo through IL-10production. In addition, lymphoma progression induced B10 cellexpansion, potentially through antigen-specific pathways as occurs ininflammation and autoimmunity (Yanaba, et al. Immunity 28, 639-650(2008); Matsushita, et al. J. Clin. Invest. 118, 3420-3430 (2008)).Thereby, CD20 mAb induces lymphoma depletion through at least twomechanisms; direct mAb targeting of lymphoma cells for depletion, andthrough the removal of host B10 cells. That B10 cells inhibitedmacrophage activation provides one explanation for reduced lymphomadepletion, but B10 cells may also negatively regulate anti-tumorimmunity. Enhanced immunity and resistance to diverse syngeneic tumorshas also been reported in studies using congenitally B cell-deficientμMT mice (Qin, et al. Nat Med 4, 627-630 (1998); Shah, et al. Int JCancer 117, 574-586 (2005); Inoue, et al. Cancer Res. 66, 7741-7747(2006)). Although the absence of B cells during μMT mouse developmentresults in significant quantitative and qualitative abnormalities withinthe immune system, increased tumor resistance has been attributed toenhanced anti-tumor Th1 cytokines, augmented cytolytic T cell responses,or CD40 ligand (CD154) expressed by tumor cells interacting with CD40expressed by B cells (Qin, et al. Nat Med 4, 627-630 (1998); Shah, etal. Int J Cancer 117, 574-586 (2005); Inoue, et al. Cancer Res. 66,7741-7747 (2006)). Since BL3750 cells did not express CD154 (FIG. 25 a),a role for B10 cells in mAb-mediated tumor depletion provides anadditional explanation for these previous studies and identifies anunanticipated mechanism through which CD20 mAb-directed therapies maywork in lymphoma patients. Moreover, selective B10 cell depletion mayrepresent a powerful new therapeutic approach for augmenting anti-tumorresponses for the treatment of lymphoma and potentially other cancers.

13. EXAMPLE 8 Generation of Antibodies that Selectively Deplete B10Cells

A panel of twelve anti-mouse-CD20 mAbs (Uchida et al., 2004, Int.Immunol. 16:119-29) was analyzed for the ability of individual mAbs toinduce homotypic adhesion of splenic B cells using methods known in theart (Kansas G S, Wood G S, Tedder T F. Expression, distribution andbiochemistry of human CD39: Role in activation-associated homotypicadhesion of lymphocytes. J. Immunol. 1991; 146:2235-2244.; Kansas G S,Tedder TF. Transmembrane signals generated through MHC class II, CD19,CD20, CD39 and CD40 antigens induce LFA-1-dependent and -independentadhesion in human B cells through a tyrosine kinase-dependent pathway.J. Immunol. 1991; 147: 4094-4102.; Wagner N, Engel P, Vega M, Tedder TF.Ligation of MHC class I and class II molecules leads to heterologousdesensitization of signal transduction pathways that regulate homotypicadhesion in human lymphocytes. J. Immunol. 1994; 152:5275-5287.)Antibodies that induced homotypic adhesion were then found topreferentially deplete splenic marginal zone B cells, which includes asignificant fraction of the regulatory B10 subset of B cells, relativeto the follicular B cell population (FIG. 27A). Furthermore, the CD20mAbs that selectively deplete both marginal zone B cells and theregulatory B cell population do so by mechanisms that are ADCC- (FIG.27B), CDC- (FIG. 28), and apoptosis- (FIG. 29) independent. Moreover,this mechanism is independent of the B cell FcγRIIB receptor (FIG. 27C).Likewise, the MB20-3 CD20 mAb that induces robust homotypic adhesion butdoes not efficiently engage most Fcγ receptors due to its IgG3 isotypedeplete B10 and marginal zone B cells, but did not deplete follicular Bcells except at high mAb concentrations (FIG. 30). Therefore, IgG3 orIgG2b CD20 mAbs with Fc regions that do not efficiently engage most Fcγreceptors but induce robust homotypic adhesion (MB20-3 and MB20-18) werecompared with the IgG3 MB20-13 CD20 mAb that does not induce homotypicadhesion for the ability to deplete B10 cells and marginal zone B cellsrelative to follicular B cells. The MB20-3 and MB20-18 mAbspreferentially induced the depletion of marginal zone B cells (FIG. 31A)and B10 cells (FIG. 31B), but not follicular B cells (FIG. 31A).Furthermore, CD20 mAbs that were capable of preferentially depleting B10and marginal zone B cells could be modified or switched to isotypes thatwould not initiate ADCC, resulting in antibodies that selectivelydeplete splenic B10 cells and marginal zone B cells, but not splenicfollicular B cells.

14. EXAMPLE 9 Anti-CD22 Antibodies Deplete the Regulatory B CellPopulation

Administration of CD22 mAbs to mice results in depletion of theregulatory B cell population as evidenced by a decrease inCD1d^(high)CD5⁺ B cells (FIG. 32A) and a decrease in B cell IL-10production (FIG. 32B).

Various publications are cited herein, the disclosures of which areincorporated by reference in their entireties.

The present invention is not to be limited in scope by the specificembodiments described herein. Indeed, various modifications of theinvention in addition to those described will become apparent to thoseskilled in the art from the foregoing description and accompanyingfigures. Such modifications are intended to fall within the scope of theappended claims.

1. A cellular composition, comprising mammalian cells enriched inregulatory B cells characterized by the ability to produceinterleukin-10.
 2. (canceled)
 3. A method for treating a disease orcondition associated with diminished levels of interleukin-10,comprising administering a therapeutically effective amount of acellular composition comprising mammalian cells enriched in regulatory Bcells characterized by the ability to produce interleukin-10 to asubject in need of such treatment.
 4. (canceled)
 5. (canceled) 6.(canceled)
 7. A method for treating a disease or condition associatedwith diminished levels of interleukin-10, comprising administering to asubject in need of such treatment, a therapeutically effective amount ofan agent that stimulates the expansion of the interleukin-10 producingregulatory B cell subset.
 8. A method for treating a disease orcondition associated with diminished levels of interleukin-10,comprising administering to a subject in need of such treatment, atherapeutically effective amount of an agent that increases productionof interleukin-10 by regulatory B cells. 9.-22. (canceled)
 23. A methodfor diagnosing a disease or condition associated with elevated ordiminished levels of interleukin-10 in a subject, comprising quantifyingthe IL-10 producing regulatory B cells in the subject.
 24. A method fortreating a disease or condition in a subject comprising administering tothe subject an antibody that preferentially depletes the interleukin-10producing regulatory B cell subset in the subject.